The film begins with a view of space as 4 silvery objects fly through an asteroid field, the opening credits roll and the ships jump into warp/hyperspace…
Cut to Tom (Carter Jenkins) at his computer, typing furiously. He’s trying to hack into his school’s website to alter his grades but is distracted by a sound outside his window. Downstairs, Tom’s mom, Nina (Gillian Vigman) is checking his grades and sees that he’s done very poorly this year. Back in Tom’s room, the window opens up and his sister , Bethany (Ashley Tisdale) crawls through, having returned from sneaking out to go on a date with her boyfriend Ricky (Robert Hoffman).
A moment later, Tom and Bethany’s little sister, Hannah (Ashley Boettcher) comes in, warning of Tom about his dad coming up to his room. Tom’s dad, Stuart (Kevin Nealon) shows up, disappointed about Tom’s grades and says that if he’s smart enough to hack into the school’s website, he should be smart enough to do well in school. Tom says that because he did so poorly, he should be punished and not allowed to go on the family vacation. Stuart isn’t fooled, and insists that they have a nice family vacation, away from distractions and technology.
Cut to the freeway, the whole family is crammed in a minivan headed for the countryside. The radio notes that there is an impending meteor shower that evening. Tom makes fun of Bethany’s boyfriend, Ricky, calling him a boy-toy. Much sibling squabbling ensues.
The Pearsons arrive at their summer house, Bethany heads for the pool, Tom explores the house, and the rest of the family unpack.
Outside, an SUV screeches to a halt, bringing the Nana Rose (Doris Roberts), Stuart’s brother Nathan (Andy Richter), and his three kids: Jake (Austin Butler), and the twins Art (Henry Young) and Lee (Regan Young)
A moment later, Ricky shows up, surprising Bethany, and irritating Tom. Ricky notes that he has to leave to get to his parent’s place, but he says that his car is having some problems and he might not be able to leave. This is a lie of course, as Tom saw Ricky remove something from his car engine to make it not start.
Ricky acts very nice and friendly to Stuart and Nina, so they like him and invite him to stay while they get his car fixed.
A while later, Ricky is at the poolside with Bethany. He does the “its awfully hot out here” trick and takes off his shirt, while Bethany ogles him. Tom is wise to Ricky’s antics but can’t really do much about it until Jake shows him his brand new paintball gun and tells Tom to do what it takes to protect his sister.
Outside, Tom and Jake are on a grassy knoll, paintball gun aimed at Ricky’s exposed back. Tom is having second thoughts, while Jake, dressed in full sniper bush-camouflage eggs him on. Jake runs out of patience and pulls the trigger, hitting Ricky painfully in the shoulder, and splattering Bethany in orange paint. Tom tries to pull the gun away from Jake, but only succeeds in catching Jakes finger on the trigger, firing even more paintballs at Ricky’s crotch. Ricky is on the ground, gasping for air while Bethany approaches Tom and Jake with murder on her mind. Fortunately for Jake, his camouflage helps him avoid Bethany, but Tom is caught and is scolded by his parents. Unfortunately for Tom, the paintball attack has added sympathy points to Ricky.
Later in the day, Nana Rose is watching TV when it suddenly goes out. Ricky, hoping to earn more points with Bethany’s parents, offers to go to the roof and fix the satellite dish, even asking or Tom’s help so they can bury the hatchet, so to speak. Up in the attic, Ricky reveals that the paintball attack just made him more popular with the parents, and that his car really isn’t broken. Ricky is a jerk to Tom, and makes him go on the roof to fix the dish while he waits in the attic.
Tom crawls through the attic window and checks out the dish, which looks like its been blown to pieces. He hears a suspicious noise and goes around the corner to check it out when Jake jumps out to spook him. The two check out the dish together and spot a large four-armed shadow of something big. They turn around to see what it is, and its revealed to be a small frog-like alien with four arms and grey skin. The alien says hi to them and seems friendly, but a slightly larger alien pushes him aside to greet Tom and Jake. After a few attempts at declaring peace, he gives up and orders the others to attack.
Just then, Ricky comes out to see what’s taking so long, only to be shot in the neck with some kind of dart and passes out. The alien that shot him, Tazer (Thomas Haden Church), uses a remote to control Ricky like a puppet, and using him to give the humans two choices, eternal slavery, or immediate death.
Tom and Jake run for it, with a mind-controlled Ricky in pursuit. Ricky trips on a cable and falls over the edge of the roof, but his foot gets caught in the cables and he is suspended over the side of the house.
Tom tries to open the attic window, but its locked. Hannah sees him but doesn’t want to open the window because there is a bug there. Fortunately, the twins show up and open the window to let Tom and Jake through. They try to tell the others what’s going on, but the aliens crash through the window in pursuit. The kids run for the attic staircase and make it down just in time to seal the aliens in the attic for the time being. Tom and Jake are both shot with the darts, but the darts seem to have no effect on them, and just fall off.
The kids try calling for help, but all their cell phones/Blackberries don’t work, they’re being jammed by the aliens. Hannah tries an old rotary phone and there is a tone. The twins don’t even know what the rotary phone is, but Tom dials 911 in hopes of getting help. Not surprisingly, the claims that their attic is full of aliens do not convince the police to send help, and before they can say any more, the line goes dead.
Up in the attic, the aliens regroup. The leader, Skip (J.K. Simmons) notes that if they screw up one more invasion, he’ll get demoted while Tazer (Thomas Haden Church) and Razor (Kari Walhgren) argue about which way is best to defeat the humans. Sparks (Ashley Peldon) questions why they want to invade earth, since the humans appear harmless. Skip tells Sparks that their last engineer thought that the species they were trying to invade were also harmless, until they ate him.
Tom suggests telling the parents and they prepare to go, but they hear a noise outside the window. They go to investigate and discover Ricky, still hanging off the side of the house. He’s still under the alien’s control, but on standby. As the others watch, Ricky starts talking, evidently relaying what Tazer is saying to the Sparks the engineer. Back in the attic, Sparks tells Tazer that the mind control plugs weren’t calibrated for children, that’s why the darts that hit Tom and Jake just fell off. Jake, Tom, Hannah and the twins try to figure out what to do next. If they notify their parents and they face the aliens, they will become slaves too. Not wanting to have to fight their own parents, the kids plan to take down the alien invasion themselves. As they decide on a plan, Ricky slips and crashes into the ground below. The kids agree to not tell anyone, but Hannah runs off to tell the parents, however, they brush it off something she saw on TV. Tom calms down Hannah while the rest of the kids come up with a battle plan. First step, figure out the enemy’s weakness. Tom and Jake climb up the side of the house to spy on the aliens. Inside, Tazer and Razor are watching the TV and catch a part of the Zorro film. There is a fight scene, followed by Antonio Banderas kissing Catherine Zeta Jones, this causes an awkward moment between Tazer and Razor (they seem to have a thing for each other, but don’t admit it). Skip tries to get them to concentrate with a bit of head knocking while Sparks sets up their locator systems. They are looking for something and it appears to be in the basement. Tom and Jake are spotted by the aliens and falls off the side into a bush.
As Tom and Jake recover, Bethany shows up, looking for Ricky. The kids hastily make up a story about Ricky going to the lake to get a tan, and tells Bethany to go find him, meanwhile, the still mind-controlled Ricky is flopped over a pile of plants and rubble, evidently still on standby.
Bethany leaves and the kids head to the basement to figure out what the aliens are after. A few moments of searching and Hannah hears a crackling noise. One of the twins pulls out his Nintendo DS and opens it, revealing complex alien writing flickering across the screen. Tom notes that something close by must be setting it off. Jake hastily gathers some tools and charges up the attic with the twins despite Tom’s suggestion to formulate a plan first. Tom also has an idea for a weapon against the aliens, but Jake ignores it and charges ahead.
Upstairs, Jake and the twins run by the parents and nana Rose, who just assumes that the kids are using the tools to fix the TV’s satellite dish. Upon arriving at the attic door, Jake fires his paintball gun at an opening in the attic‘s hatch,. Thinking that he’s beaten the aliens, Jake celebrates, until a small silver grenade-like device is thrown through the opening and bounce towards Jake and the twins. The grenade doesn’t seem to do anything and the kids think its just a dud, until it suddenly reduces the gravity to zero, causing the three boys to float upward, flailing about harmlessly.
Downstairs, Tom has built a potato gun and head upstairs, followed by Hannah. Razor and Tazer come down from the attic and make their way across the floor with the help of gravity/suction boots. Tom shows up and fires a potato at the aliens but misses, and ends up being thrown across the room. The aliens are about to reach the door to the lower level but Tom spots a fire extinguisher and manages to propel himself to the door to lock it, then turns the extinguisher on the aliens. However, the extinguisher runs out and Tazer floats himself up towards the ceiling to unlock the door (it has one of those sliding locks near the top).
Realizing that the aliens are trying to open the door, Tom gets Jake to grab the grenade and to throw it at Tom, who uses the extinguisher like a bat to destroy t gravity grenade. As the grenade shatters, gravity is restored and everyone hit’s the ground. The aliens, having no other choice, escape back towards the attic, with Tazer taking several paintball shots to his backside and dropping some devices before getting back into the attic.
The twins discover the device and figure that it’s the same controller for Ricky. They mess with the buttons, causing Ricky to run around randomly before he runs into his own car and causing a huge dent. Jake stands watch at the attic while Tom and the Twins go looking for Ricky.
Outside, the twins find Ricky and have fun making him slap himself until they discover the off button to restore him. As they do, Ricky goes nuts over the dent on his car and yells at Tom until the twins freeze him with the controller. Bethany shows up after waiting for Ricky at the lake for an hour and is none too happy. Tom signals the twins to release Ricky, who continues to yell, but now he’s yelling at Bethany instead of Tom. This angers Bethany and causes her to slap Ricky, then storms off angrily with Ricky chasing after her, having no idea of what has been going on.
Back upstairs, Tom and the twins rejoin Jake and Hannah and discover that the aliens are making their way through the vents to get to the basement. Tom turns up the thermostat and the aliens are driven back temporarily. Downstairs, Stuart yells at Tom for all his weird actions, and his failing grades. Tom reveals that he failed his courses on purpose so others won’t think he’s such a nerd. Stuart relents a bit, but tells him not to touch the thermostat.
The kids regroup and come up with a plan to temporarily get the adults out of the way so they can battle the aliens. Jake sets up a webcam to a RC car and puts it into the vents to spy on the aliens, while the twins go to retrieve Ricky.
Ricky and Bethany are at the lake and have made up. Ricky tries to “advance the relationship” with Bethany, who thinks that things are going a bit fast, but before she is able to say so, Ricky’s mind control plug is reactivated by the twins and he ends up throwing Bethany into the lake before swimming back to shore (funny scene).
Back with Jake and Hannah, the RC is discovered by Skip, and it is destroyed.
Jake and one of the twins take control of Ricky and use him to trick the parents into leaving the cottage, making them think that there is a problem with the house’s leasing agreement and that the leasing office is cutting off their phones and power. Tom’s parents, along with Jake’s dad head out while Ricky stays to “baby-sit.”
Back at the vent, Jake is making use of his dad’s huge box of fireworks, gassing and bombing the vents. The aliens are separated and Sparks falls through a vent and into Hannah’s room. Sparks gets himself stuck in Hannah’s slinky, thinking it’s a snare trap. She even puts a bandaid on his injury and they start making friends. Up in the vents, the others discover that Sparks has fallen behind. Sparks is necessary for their mission and they plan to get him back.
Hannah is playing with Sparks and he helps fix her bubble gun toy, but the others charge in thinking that its holding a gun at her. She explains that Spark isn’t like the others. They figure out that Sparks or “snuggle lumps,” as Hannah calls him, is harmless, and is the alien’s engineer.
Up in the vents, the others discover that Sparks has become friendly with the aliens.
In the kitchen, Bethany has finally got out of the lake and finds Ricky, who is still frozen in standby mode with his back to Bethany. Bethany tries talking about their relationship and thinks that he’s giving her the silent treatment and storms off.
The kids are now trying to interrogate Sparks as to why the aliens have come to their summer house and Sparks quickly draws them a diagram of their house and what they’re looking for. The alien’s objective is a large silver disc that is buried beneath the house. Sparks shows them what the machine looks like using legos, but isn’t able to explain what it is because he can’t speak English.
Meanwhile, nana Rose is still in the house and is ambushed by Tazer with a mind control plug.
While this is going on, the parents show up at the leasing office but find that its closed.
Back at the house, Sparks helps Tom upgrade his potato gun but is quickly interrupted when a mind-controlled nana crashes through the door demanding that they return Sparks. Nana is about to reach Sparks when Tom slides a skateboard under her feet, causing her to slip and fall, revealing that Skip was hiding under her dress. Skip demands that they return Sparks and Hannah fires her bubble gun at him while Tom traps him in a fishing net. Jake opens up Hanna’s toy box and locks Skip inside. Tazer and Razor show up to retrieve Sparks. They grab a suitcase, thinking Sparks is in it, and run for it. Unfortunately for them, the suitcase is filled with Hannah’s toys and Skip is still locked in a box.
Outside, Sheriff Doug Armstrong (Tim Meadows) finally shows up to warn the kids that prank calling 911 is a serious offence. Jake goes off alien hunting while Tom, Hannah, and he twins go to face the sheriff, along with the box holding Skip.
Outside, the kids are trying their best to apologize and to make the sheriff leave but he gets suspicious of the box. Through the keyhole, Skip sees the officer’s gun and identifies it as a weapon he can use. The sheriff insists on checking out the box but the parents show up, thinking that the kids have gotten into trouble.
On the roof, Tazer aims his control plug gun at the parents and prepare to fire. Tazer identifies the cop as the one armed with a weapon and is about to hire a plug at him but Jake throws a crowbar at him, making him miss. Jake chases after Tazer but is ambushed by Razor using his own paintball gun. Jake is hit and knocked off the roof.
Downstairs, the parents invite the sheriff to a barbeque as a peace offering. Nana Rose has recovered from her mind control and has no idea what’s been going on. Bethany is still fuming about Ricky ignoring her, and Jake is still missing but nobody seems to notice apart from the kids.
Back with the aliens, Jake has been tied up and gagged and being dragged down the stairs.
Everyone else is having barbeque while Skip slowly tears his way out of the box and escapes with the controller to Ricky’s brain.
Razor and Tazor are digging into the basement looking for the alien device.
Ricky shows up at the barbeque demanding surrender and pushing Bethany aside, calling her a “hormonal female.” Bethany is angered again and runs off. Ricky then attempts to retrieve Sparks, grabbing Hannah’s back pack and runs off. The kids pursue but Stuart tries to stop them, thinking that they’re up to no good. Fortunately, the twins use another controller and gets nana Rose to tell everyone they’re off to play a game and they all run off.
Ricky throws the bag with Sparks into the basement and prepares to eliminate the kids. The twins come in with nana and a pretty neat fight ensues. Bethany shows up just as nana elbows Ricky in the neck, disabling the mind control plug. Ricky has a short, confused moment before being matrix-kicked across the room and through the basement door, much to Bethany’s horror.
At the same moment, Bethany spots Skip hiding on a ceiling light and screams, finally realizing that there really are aliens in the house.
Tom is on the verge of giving up but Bethany demands that they go save Ricky. Everyone rallies together and prepare to storm the basement to save the world, and Ricky. The kids descend the stairwell and find the hole in the basement, but nothings there. Something moves and they realize that its Jake. Jake reveals that the aliens had sent something to Earth many years ago to aid their invasion plan, but built a house over it.
Outside, Sparks is made to activate the machine and it begins to unfold into a platform. The kids see this and decide that they have to stop them and Jake has a plan. Throughout the day, nana has been giving the kids candy, Mentos. So Jake gathers up all the Mentos and prep several Diet Coke bombs. The aliens prepare to activate the machine when several Diet Coke missiles fly in, disrupting things.
Razor is knocked into a recycling bin and trapped but Skip is knocked into the machine, making him huge (size of house). Tom has an idea and uses the machine to enlarge the control plug gun. While in his enlarged state, Skip plants the beacons he had on him (now also enlarged) and sends a signal into space. The adults see this, but think its part of the meteor shower/fireworks.
Tom is able to fire the over-sized control plug at Skip and use him to fight a now enlarged Tazer. The two giants duke it out while Sparks reverses the machine. Tom makes them both fall into the machine and an explosion occurs, reducing the two aliens back to normal size. The machine begins to fold in on itself and teleports away, taking the aliens with it.
The rest of the invasion fleet arrives, Sparks tells them that the invasion has been foiled and they retreat back to space. As the alien spaceships fly off, Hannah wants Sparks to stay, but he shows her a picture of his own family and they have a tearful goodbye as he returns home in his little ship.
Later that evening, Tom talks to his dad and they reconcile, he even fixes his dad’s broken fishing reel.
The next day, everyone goes fishing and have fun. A little while away, Skip crawls out of the water, bent on revenge (he was apparently thrown clear when the machine collapsed). But, before he can do much, he is carried off by a large bird.
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