NOTE: This spoiler sent in by William.
The film begins in outer space.
A damaged ship tumbles through space and falls towards earth. As it enters the atmosphere, it starts to break up. Down below in Norway, 709 AD, a Shepard watches as the ship crashes into a lake, scattering burning debris everywhere.
As the remains of the ship sinks into the water, something glowing and organic moves towards shore. On the other side of the lake, two figures wearing space suits float up and swim to shore as well. One of men is hurt and the other tends to him. The uninjured man, Kainan (James Caviezel) passes out shortly after.
The next morning, Kainan comes to and checks on his partner, but the man has died apparently dead from large claw wounds he received prior to the crash. While taking a moment to gather his bearings, Kainan hears a beeping sound from a long triangular crate floating in the water, and goes to retrieve it. Back on shore, Kainan opens the crate, which appears to be an emergency survival kit/computer. The computer speaks to Kainan in an alien language and Kainan asks it regarding his current location. A hologram reveals that he is on Earth (an “abandoned seed colony”), in the Iron Age. Kainan tells it to search for nearby vessels but there are none nearby. Kainan then asks the computer what the local language is, and it replies that it is Norse, and proceeds to download the language in Kainan’s mind via an eye piece it seems painful. Recovering, Kainan retrieves a gun /cannon from the box and tests it out; blowing up a tree, then activates the computer’s distress beacon. As darkness falls, Kainan buries his friend.
The next day, Kainan heads into the woods and soon finds the carcass of a whale, along with a burned and abandoned village. There are clear signs of a struggle (claw marks on the doors, broken swords, etc.). Kainan hears something and chases after it, and is immediately knocked out by a man on a horse. Kainan’s weapon is knocked into a river and lost.
The man that knocked out Kainan, Wulfric (Jack Huston) drags him back to his village. The village is surrounded by a high, circular wooden barrier, with a longhouse (kind of like a town centre where dinners, parties, and meetings are held) in the middle.
Inside the longhouse, Freya (Sophia Myles) is sparring with her father, king Rothgar (John Hurt) while arguing over the man she is suppose to marry. Freya does not want to marry Wulfric and believes that he will become a tyrant and a butcher, like his father. Rothgar relents and asks her to choose someone else, but Freya refuses to name another. While sparring, Rothgar cuts Freya in the arm and stops to treat her injury. Rothgar wants someone to take care of Freya when he’s gone, and believes that Freya can help Wulfric become a good king. A moment later, Wulfric barges and upon seeing Freya with a sword and shield, says that no queen of his should fight like a man Freya is far from impressed. Wulfric informs Rothgar that a neighbouring village has been sacked; no survivors were found, not even bodies, and it does not appear to be the work of raiders. Wulfric notes that he found a man in the woods and Rothgar asks him to find out the truth. If they don’t figure out who is responsible for the massacre, the other tribes will start blaming one another and war will break out.
Kainan is tied up and his armour is taken away. Wulfric interrogates Kainan, asking him where he comes from and why he attacked the village. Kainan lies about where he’s from and tells Wulfric that he did not destroy the village, and that he was out hunting. Wulfric asks him what he was hunting, and Kainan points to a dragon symbol on the wall. The others don’t believe him and beat him for answers. Kainan tries to escape, but is quickly subdued and knocked out again.
Wulfric goes to the long house to visit Freya, who is preparing food/medicine with the other women of the village. Wulfric asks for her help in treating Kainan, and she reluctantly agrees.
Kainan wakes up and is tied to a pillar inside the blacksmith’s cabin. He pulls a hot metal rod from the fire and burns through the ropes (and a portion of his foot). As Freya comes in, Kainan pretends to be still tied up and unconscious. Freya comes in and washes Kainan’s face; she is clearly intrigued by this stranger.
Outside, Wulfric and Rothgar discuss the “outlander” (Kainan). Wulfric tells him about Kainan’s story about hunting a dragon. Rothgar wants to send news to Gunnar, the leader of the destroyed village who has been away hunting/trading. Wulfric just wants to kill Gunnar, because if he sees his village destroyed, he will blame Rothgar and tell the other tribes, resulting in war. However, Rothgar notes that Wulfric blames Gunnar for his father’s death and he may be biased.
Back at the blacksmith’s hut, Freya continues to clean up Kainan. He wakes up and she asks him if he attacked Gunnar’s village and he says no. Freya sees that Kainan has cut through the ropes and he knocks her out and the guard as well. Kainan steals the guard’s clothes and leaves. At the outer wall, the guards along the walls do not see Kainan as he sneaks by. Suddenly, there is a breeze and they smell something rotten. The guard looks down and sees nothing, but then turns around and sees a glowing red tentacle that lunges at him. The other guards realize that someone is attacking and raises the alarm. All the men of the village charge out but do not see any attackers.
Inside the village, one soldier runs home to get his sword by is promptly torn through a wall by a mass of the glowing red tentacles.
Rothgar orders Wulfric and some men to investigate the sounds coming from inside the village. In a stable, another man investigates some suspicious noses, and is killed by the creature. Kainan spots the beast and runs after it. The guard that was watching Kainan sees him, and gives chase. Kainan follows the creature to an area where animal skins are hung to dry. The guard thinks Kainan is on the other side of an animal skin and attacks, but it’s the creature and the guard is killed. The creature makes it way over the main fence/barrier and Kainan finally gets a good look at it, calling out its name, “Moorwen.”
Rothgar and his men finally catch up but the creature is gone, but they do catch Kainan though. Kainan is tied to a rock and watches the damage caused by the creature and has a flashback to his past. In the flashback, Kainan runs home only to see his home in flames and his loved ones dead. Back to the present, Kainan is still tied to a rock and is being watched by a small child, who tosses Kainan a piece of bread. Kainan is dragged off to speak to Rothgar and the council. The village elders are arguing about what could have caused the carnage from the previous night. Many theories are presented: raiders, wrath of God for following Pagan rituals, etc.
Rothgar questions Kainan about the dragon he mentioned earlier, since it seems evident that the men were killed by a large beast of some sort. Kainan replies that his people call it a “Moorwen.” The moorwen draws its victims in with light it creates (bioluminescence), and smells like death. Rothgar says there is no such thing but Kainan replies that there is now, because he brought it here. The moorwen somehow got onto his skip, killed the crew, and damaged the ship, causing it to crash.
Kainan knows that they intend to hunt the creature, and wants to be allowed to go with them. Although Rothgar is still sceptical of Kainan’s story, Kainan has been declared not responsible for deaths that have occurred, so Rothgar allows him to join the hunting party. Kainan is about to mount his own horse and is punched in the face by Freya (payback for knocking her out earlier). The child (the one who gave bread to Kainan) watches on as he leaves with the other men. Boromir (Cliff Saunders) seems friendly and offers Kainan a drink, making conversation and laughing along the way. Rothgar asks more about the creature and Kainan tells him that his own village was destroyed and he was transporting the dead when the creature must have gotten aboard his ship.
The men separate to cover more ground and Wulfric is paired with Kainan. Boromir and Rothgar find a trail of blood and follow it into the woods. Two other soldiers follow another trail of gore to a cave. Wulfric and Kainan track the creature to the shore of a lake, but see no sign of it however, the creature is hiding under the water and sees them. Kainan senses the creature but can’t see it. They hear a scream and voices claiming that they’ve found the moorwen. As everyone arrives to fight the creature, it turns out to be a bear. Rothgar is about to be killed but Kainan charges in to save him, grabbing a sword, and stabs it. Wulfric helps Kainan, and together, they kill the bear.
Outside the cave, Rothgar frees Kainan for saving him and gives him a sword. Back in the village, everyone is feasting and drinking to celebrate the slaving of the bear (they think it was the moorwen, and the one responsible for the all the recent deaths). Wulfric is treated like a hero for killing the bear, and when Kainan arrives in the longhouse, he too is celebrated as a hero.
A drunken Boromir tells Freya of how the bear was killed by Kainan, and she appears impressed. The child from earlier (the kid that was nice to Kainan) is in the hall and he seems to like hanging around Kainan. Rothgar tells Kainan that the child’s parents were killed last year when the village was raided. Kainan lets the child play with his sword, in exchange for his name, and the kid tells him that his name is Eric. Eric runs off to play with the sword. Suddenly, one Viking yells out: “shield!” and everyone grabs their shield and raises it up over their shoulders, then arrange themselves in a large rectangle along the walls of the building. Wulfric stands up and picks Kainan. Wulfric gets on a shield, and so does Kainan, who has no idea of what to do. Wulfric tells him to follow and Kainan does so. Both men walk/stumble across the shields while the crowd cheers on. The goal seems to have one man chase the other until one catches up, or falls (drinking along the way). Wulfric is the village champion but Kainan is doing a good job as well. Wulfric then challenges him to do a forward flip while on the shields, Kainan tries, and successfully lands on Boromir’s shield, until it breaks and Kainan falls on top of Boromir. Wulfric is still impressed by Kainan, and helps him up, the crowd cheers.
Later that night, Kainan is outside practising with his sword and almost hits Freya, who has come out to thank him for saving Rothgar. Freya seems to like Kainan, and says that all the women are talking about him. Kainan reveals that it was not the bear that killed their people, and that the creature that did will return. Suddenly, raiders lead by Gunnar (Ron Perlman) attack the village, taking the sentry guards by surprise. Kainan saves Eric from a raider and runs off to join the other men while they attempt to repel the enemy. Gunnar seeks out Rothgar and attempts to kill him because he believes that Rothgar and Wulfric are responsible for destroying his village and killing his family. Gunnar is about to kill Rothgar but Kainan comes in at the right moment and saves him. Gunnar’s forces are beaten and are forced into retreat.
Kainan goes to Freya, who treats his injuries. Kainan asks who Gunnar is, and why he would immediately blame Rothgar and Wulfric for the destruction of his village. Freya tells him that years ago, Wulfric’s father had rallied the tribes against the Franks, but Gunnar’s tribe was held back while fighting another enemy. Gunnar’s tribe never arrived and Wulfric’s father was killed; Wulfric blames Gunnar for his father’s death, and Gunnar believes that Wulfric destroyed his village as revenge.
Out in the woods outside Rothgar’s village, Gunnar and his remaining men set up camp and plan their next attack. One of Gunnar’s men separates from the others to relieve himself and is killed by the moorwen. The other men are slowly picked off but Gunnar and a few others are able to escape towards Rothgar’s village. Wulfric sees Gunnar and his men coming towards him and gives the order to let loose with the arrows. Several more of Gunnar’s men are killed before Kainan realizes that they are not charging, but in fact, running for their lives. Kainan stops Wulfric, and opens the gate to let them in.
One of Gunnar’s men isn’t so lucky and is dragged away by the moorwen. At this point, everyone realizes that all the deaths have been caused by this creature, and not each other, and finally agree to set aside their differences and work together. Gunnar, Wulfric, and the other warriors argue over what to do. Wulfric wants to hunt the creature, but Kainan tries to talk some sense into him. Kainan suggests building a trap, Rothgar agrees, and they immediately get to work. In the morning, the villagers chop down wood and form a cage. The cage has a deep pit, which is filled with flammable oil. There are posts placed inside the pit, which support a series of shields. As the sun sets, Rothgar speaks to Kainan and asks him to stay after they kill the creature.
Cut to the moorwen’s lair, the unfortunate man that was dragged away earlier is still alive. As he wakes up, he sees that the moorwen is giving birth, and is immediately killed by the newborn.
Back at the village, Kainan visits Freya to who makes him some dinner and they talk. Freya believes Kainan to be a good man, but he blames himself for everything that has happened. This begins a flashback. Kainan was responsible for finding habitable planets for settlement. Kainan and his people found such a planet, but it was inhabited by millions of moorwens (their home planet). To make the planet safe for humans to live, Kainan and his people nuked the planet, and then systematically hunted the creatures to extinction. After the moorwens were eradicated, Kainan was given a piece of land as payment, and he lived there with his wife and son. One day, Kainan was sent on a mission and he leaves his wife and son, telling them that they will be safe. However, three weeks later, Kainan receives news that there had been one mooren that survived the genocide and it destroyed the settlement, and killed everyone. Kainan returned to find his home in flames, and his family dead. After hearing his story, Freya is saddened, but still believes that Kainan to be a good person, since he has stayed to fight the moorwen and defend her village. Freya give Kainan the king’s sword meaning that she wants him to be the next king, and implying that she wants to be his queen.
Outside, Wulfric is waiting for Kainan, and seems to know what’s going on between them, and accepts it. Everything is ready and they prepare for the assault. Wulfric and Kainan walk outside to lure the moorwen into the trap. Out in the distance, they see something, and Kainan throws his torch, revealing the adult moorwen. They slowly head back into the fort to draw it in, but the preacher comes out and tries to exorcise it, thinking that it’s the devil. The priest is torn apart and the creature charges after Kainan and Wulfric. The two men run across the pit, over the shields. Wulfric gets knocked down but Kainan pulls him out just in time. The moorwen falls into the pit of oil, and Rothgar orders the pit to be set on fire flaming arrows rain down and the pit explodes.
While this is happening, a man is delivering arrows to the front lines and spots a red glow coming from a well. Boromir turns around and the man has disappeared (presumably killed by the smaller moorwen that has snuck in through the well). Freya, the women and the children have barricaded themselves inside the long house while the men fight the moorwen. However, Eric spots the younger moorwen and alerts Freya, and everyone tries to run for it. Outside, Rothgar hears the women screaming and rushes towards the longhouse.
The larger moorwen is still alive and burst out of the pit, on fire and very angry. Everyone tries to kill it but can’t seem to do much damage. Wulfric is knocked aside, and Gunnar is decapitated by the creature’s tail. The moorwen escapes, tearing a whole through the main gates. Eric runs to Kainan and tells him about the smaller creature. Kainan runs to the long house to find that the newborn moorwen has escaped as well, and that king Rothgar has been killed.
Now with two moorwens on the loose, and the king dead, the people of the village prepare to evacuate towards the shore, intending on leaving the region on boats. Eric wants to stay, but Kainan sends him off, promising to help them return some day soon. Wulfric is now king (he’s the default choice in case of the king’s death).
Kainan, Wulfric, Boromir, Freya and several others stay behind to stop the moorwens. Kainan figures out that the smaller moorwen had entered the village through the well, and believes that they can use it to locate the creature’s lair. Wulfric points out that they need better weapons but Kainan says they need better metal. Kainan and gets Boromir, Unferth (Patrick Stevensen) and Olaf (Ted Ludzik) to prepare the forge while he, Wulfric, and Freya go to retrieve metal from the remains of his ship.
At the lake, Kainan dives underwater to retrieve scraps of metal from his ship, and is pursued by the smaller moorwen. The creature disappears and Kainan swims up the surface and finds the boat shattered, and Freya missing. Back at the village, Boromir re-forges the king’s sword with the metal from Kainan’s ship, producing a sword that is capable of cutting through the moorwen’s thick skin.
After arming themselves, the five remaining men go down the well and swim through the underwater pathways into a series of subterranean caves.
Inside the moorwen’s nest/lair, Freya wakes up, injured, and in a pit of dead bodies. She tries to climb out, but is stuck underneath several corpses.
Kainan and his party continue their hunt for the moorwen, but Olaf and Unferth is attacked and hauled off. Wulfric finds the smaller moorwen and they attempt to flank it. Wulfric gets a good swing in and blinds it, but it escapes and severely injures Boromir, who dies shortly after. Kainan gives off a “NOOOOOO!!” which is heard by Freya. They head towards each other’s voices but Freya runs right into the smaller moorwen. Luckily, it was injured by Wulfric and appears to be blinded. It still has a sense of smell, and slowly makes its way towards Freya. Wulfric and Kainan try to help but they’re separated by a wall of rock. The moorwen gets close enough for Wulfric stabs it through a hole in the wall, and Kainan tosses his sword to Freya and she kills it, avenging her father.
By this point, the larger moorwen has awakened, discovers that its young has been killed, and is very pissed off. The three remaining humans try to escape through a river way, but end up at the edge of a cliff over a raging waterfall. They slowly make their way across a ledge but Wulfric stays to fight the moorwen to buy them some time. In the fight, the moorwen gets Wulfric in its jaws and mortally wounds him, but not before he injures it with a knife to its neck. Freya is now safely on a ledge and Kainan confronts the creature himself. The moorwen seems to recognize Kainan, staring at him for some time before backing off into the waterfall.
Kainan has no choice but to follow it back into the caves and hunt it down.
Outside, Freya does not want to leave Kainan, and climbs back towards the cave to help.
Inside the cave, it is dark and there is water everywhere. The moorwen sneaks up on Kainan and knocks him down. It is about to kill him but Freya arrives stabs it in the back with sword. The moorwen tries to jump out of the way, but crashes through several rock pillars and rolls out of the cave entrance and over the edge. Before it falls off the edge, it grabs onto Kainan. Now Kainan is hanging onto the ledge with the moorwen holding onto his leg, and Kainan is hanging onto Freya. He reaches for his sword and slices the moorwen’s arm off and it falls hundreds of feet down to the water and rocks below.
Freya and Kainan tend to Wulfric, who gives Kainan the king’s medallion and dies in Freya’s arms. Freya and Kainan climb up the cliff and see the villagers on their boats, about leaving the land. Freya and Kainan call out to the boats, and are spotted by Eric. Kainan tells Freya to wait for her people to come back for her, but he has to leave. They kiss, and Kainan heads off into the wilderness.
The next scene shows Kainan under water, swimming back to his ship. Inside, he finds the coffin/pod containing the body of his wife, he seems to say goodbye to her and swims back up to the surface. Kainan returns to shore, and to the computer. Kainan looks at it for a while, then takes his sword and destroys it, and returns to the village. Freya has been following him and sees this thinking that the homing beacon was sent by the gods to call Kainan home.
At the village, the bodies of the dead (Rothgar and Wulfric) are given a Viking funeral (put onto boats, set on fire).
Freya gives a voiceover, describing Kainan as being sent by the gods to slay the moorwen, but when it was time to leave, he chose to stay (when Kainan smashed the distress beacon/computer). She goes on to say that he took a wife (married Freya), adopted a child (Eric) and became king.