NOTE: This spoiler was sent in by Caboose who says..."Best western I've seen in a long time!"
The movie opens late one night on the Evans family’s ranch (which is out in the middle of nowhere). Dan Evans (Christian Bale) is awoken by someone setting his barn on fire. The man that torched the barn tells Dan he has a week to pay someone named Hollander or he’ll come back to burn their house down. After the man leaves, Dan and the oldest son William race into the barn to save their horses/equipment/etc. William goes back in to get one last saddle, but Dan runs in to get him out before the barn collapses. It’s pretty obvious that Dan is over-protective on William and the younger son Mark. The next morning, Dan’s wife Alice (Gretchen Mol) tells Dan that she thought their debt was all paid off (Hollander is obviously the man the Evans’s owe money to); Dan has paid some of the owed money, but he needed to save some in order to put food on the table. Dan then heads out with William and Mark to go retrieve some loose cattle. As he leaves, he takes a piece of Alice’s jewelry with him (important later).
On the other side of the canyon, Ben Wade (Russell Crowe) is drawing a picture of an owl when he is interrupted by his men riding by horseback to tell him some news. The men plan to rob a stagecoach full of money that’s soon passing by, so Ben finishes his owl drawing and gets their plan into action. Ben’s comrades, led by Charlie Prince (Ben Foster) are to charge the wagon while Ben and a Mexican sharpshooter watch from the hills above. The crew gets spooked for a second when they hear a gunshot (which was Dan on the other side of the canyon), but they get back to the plan. The wagon emerges, and the men start attacking it; what they didn’t expect is that a bounty hunter named Byron McElroy (Peter Fonda) is onboard the wagon and starts picking off the men. Ben gets an idea to chase some cattle off the hills and into the wagon’s way; the plan works, and the wagon crashes sending McElroy and a few others flying off it. Charlie gets off his horse and kills all the men from the wagon except for McElroy (Charlie shoots him, but Ben tells him not to kill him). The group gets the money, but one remaining wagon rider jumps out and holds one of Ben’s men hostage; as this happens, Dan and his sons ride through to see this happen. Ben quickly grabs his pistol and shoots both his man and the wagon rider. As Ben and his men grab the money and head out, Dan stops them because the cattle that Ben shooed off the mountain were his. Ben tells him he can have his cattle, but he wants Dan and his sons’ horses (that way, they can’t get to town to tell the Marshall what happened). Dan agrees; Ben takes their horses and rides off with his men and the money.
After the heist, Ben and his men go to a local town named Bixby, where they begin “phase 2” of the plan Charlie goes into the Marshall’s office and tells him he witnessed Ben Wade rob and trash the stage coach. After all the officers leave to go investigate, the group rendezvous at the local saloon. After a few shots of whiskey (and a toast to the comrade Ben had to kill), the men exit the saloon, leaving Ben to hit on the waitress. Ben tells her she reminds him of someone, and after a few minutes of flirting, they kiss and head to the saloon second floor. Meanwhile, Dan and his sons’ end up finding their horses (seems like Ben was generous enough to give them back) and an almost-dead McElroy. All the marshals from Bixby arrive and Dan tells them everything that happened. When the marshals ask Dan which way Ben went, Dan tells them, “they looked like they were heading towards Bixby.” (OOPS!)
When the marshals and Dan (the boys went back home, I guess) arrive back to Bixby, Ben is still in the saloon drawing the waitress naked. They take McElroy to Doc Potter (Alan Tudyk) to get the bullet out; in a funny scene, we find out Potter is more of a veterinarian than a people doctor. Meanwhile, Dan bumps into Hollander and the man who burned down his barn (his name is Tucker, btw) and begs to give him more time. The problem with Dan’s land is that it’s too dry and he needs money to build a well, but Hollander won’t help him and heads to the saloon. Dan eventually grabs his gun and heads to the saloon to threaten Hollander; instead of finding Hollander, he finds Ben. Ben immediately recognizes Dan and asks if he got his cattle/horses back; Dan agrees but he wants reparations for a few dead cattle. Ben gives him a couple bucks, but Dan asks for an extra five dollars “for making him nervous”. Suddenly, the marshals arrive and arrest Ben. Everyone starts talking about Ben’s punishment (he’s going to get hanged) and the plan to transport him to a town called Contention (or something like that) where he will board the 3:10 to Yuma and be on his way to prison. Potter, McElroy, Tucker, and a railroad expert named Butterfield are chosen to escort Ben to the train; Dan also volunteers to escort Ben if he gets $200. As they take Ben to the stagecoach, Charlie and the rest of Ben’s comrades show up and start shooting the townspeople. The group quickly gets Ben in the stage coach and drive off.
Before the trip to Contention, the group stops at Dan’s ranch for dinner. During dinner, Ben asks where Dan got a scar located beneath his eye; Mark starts telling a story about how Dan fought to protect the District of Columbia. A minute later, the guys go outside once Potter and Tucker start shooting at something they saw in the hills (Charlie followed them). As everyone leaves, Ben makes small talk with Alice, asking if she’s ever been to San Francisco. They have a good talk until Dan comes back in and tells Alice not to talk to her. Alice then asks Dan why he’s escorting Ben; he tells her because they need the money. After dinner, the guys are ready to go on their trip. William asks to come, but Dan refuses. In the middle of the night, William ends up sneaking out and going after the guys.
As the guys make camp for the night, Ben asks Dan to talk about his war story and how he has a bum leg from it; Dan threatens to choke Ben when he makes a comment about Alice. The others pull Dan off Ben and all get ready to sleep. Tucker makes a lot of noise and keeps Ben up all night; this results in the other guys waking up to Tucker dead on the ground (Ben killed him with a fork he stole from Dan’s house). McElroy is furious and beats the crap out of Ben, but they end up pulling him off and getting ready to ride on.
Somewhere else in the canyon, Charlie and the other guys track down a stage coach they think Ben is in. When they find out it was a set up, Charlie lights the wagon on fire and tells the person locked inside that he will burn to death if he doesn’t give him answers. The person caves in and tells Charlie everything, but Charlie still lets him burn to death. He tells the other guys that they’re heading to Contention.
Meanwhile, Dan suggests to the group that they take a shortcut despite Ben’s warnings that the shortcut goes through Apache Indian territory. As they ride through the cliffs, Ben learns that Dan had his leg blown off at the war he was at, and the government paid for how it got fixed. As this point, McElroy tells Ben to stop talking to Dan; suddenly, Ben gets the drop on McElroy and puts a gun to his head. The others comply and toss their guns as Ben throws McElroy off the cliff, killing him. Suddenly, William shows up behind Ben and puts a gun to head. Dan is angry William snuck out, but now he has no choice but to let William come with him. As they camp out that night, the guys are attacked by Apache Indians, but Ben grabs a gun and kills the Apache, saving the other 4 guys.
The next day, Ben makes another escape attempt by stealing a horse and riding to a spot where a railroad is being built. Ben begs one of the Chinese railroad workers to break his handcuffs, but the two men who own the worksite (one of the men is Luke Wilson in a very recognizable cameo) and immediately recognize him apparently Ben killed one of the guy’s brother. Dan, Potter, William, and Butterfield catch up and are surprised to find Luke Wilson electrocuting a tied up Ben the two railroad workers refuse to give up Ben. The guys eventually get Ben back, but they get chased by horseback through the caves. One of the railroad workers ends up shooting Potter as they ride away. When they get far enough, the guys get Potter off his horse; Right before he dies Potter asks, “Did we make it out?” Dan replies "yes because of you." An hour (or two) after the guys leave, Charlie and his men drive through the work site to ask if Ben Wade rode through. Luke Wilson and the other guy put up a bit of an attitude, so Charlie shoots both of them dead as they ride on.
Finally, the remaining good guys (which is now Dan, William, and Butterfield) get Ben to Yuma and decide to put him in a motel so he can lay low (the 3:10 to Yuma doesn’t come for another hour). While Dan guards him in the hotel, Ben offers to pay all of Dan’s debts off if he lets him go; Dan is hesitant, but still says no. William runs up to the hotel and tells everyone that Ben’s posse is coming. When they get to Yuma, Charlie finds out what hotel Ben is at (thanks to the narc running the hotel) and asks to speak to Ben. Ben sticks his head out the window, tells Charlie he’s fine, and insists he and the boys go to the saloon for a drink (of course, Dan made him say that). Charlie then cooks up an idea to give $200 to any townsperson that helps kill everyone guarding Ben. The marshals are cowards and tell Dan and Butterfield that they are quitting and they walk outside to surrender but are shot down anyways. Now Dan is in a tough situation. Butterfield decides that maybe it is time to let Ben go, so he offers the $200 he promised Dan as reward money if he lets Ben go. Dan thinks, but still says no; Dan still wants justice delivered for Ben Wade. As Dan tells William to stay with Butterfield, he gives William the jewelry he took from Alice in the beginning and tells him to give it back to her if he doesn’t live. Obviously, William doesn’t really like rules, so he eventually runs from Butterfield to go help his dad.
So the epic battle begins. Dan tries sneaking Ben out the back, but sharpshooters are waiting. Dan starts going through the town shooting everyone in sight and dodging as many bullets as he can. Charlie gets angry when he realizes the townspeople are starting to shoot at Ben (obviously thinking he’s the target), so he starts shooting the townspeople too.
Ben and Dan duck into a general store where Ben beats up Dan and makes yet another escape attempt. Dan is being strangled by Ben when he blurts out that he's not a hero at all, and he tells Ben the reason he took the job of taking Ben to the train. He confesses that his leg was shot off by one of his own troops when they were retreating in the Civil War. He asks Ben to imagine the way his boys looked at him after he told him that story. Ben realizes that Dan is doing this for his sons (and possibly everyone else) to respect him again, so he cooperates with Dan as they climb up to the roof and run on the rooftops. The posse continues shooting, but they miss as Dan and Ben make it to the train station.
When they get there, it’s officially 3:10pm…..but the train is running late (D’OH!) As they wait, Charlie and the posse start taking positions around the train station that pretty much has Dan pinned into the station. In the station, Dan reveals to Ben that Mark was diagnosed with tuberculosis and can only survive in a dry climate; this explains why Dan’s ranch is out in the middle of nowhere. Ben also realizes that Dan is starting to trust him. A few minutes later, the train arrives, but Dan can’t get Ben on it because they are pinned by Ben’s posse. As Charlie waits in his position (which is in the middle of a cattle farm), William sneaks behind him and opens one of the gates. The cattle go crazy, causing Charlie to lose his eye on Dan. Dan sees this and gets Ben onto the train; as Ben gets locked into one of the train cells, he tells Dan that it’s been a pleasure. Suddenly, Charlie comes up behind Dan and shoots him a few times. Charlie forces the train worker to release Ben, which he does. Ben looks down at Dan’s body and is shocked. As Charlie gives Ben his gun back, Ben turns the tables and quickly shoots all of his posse and Charlie. He grabs Charlie and shoots him again in his bullet wound, killing him. William runs to Dan’s side and talks to his dad with pride in his father that he got Ben to the train but Dan quietly dies. William grabs Dan’s gun and points it at Ben, but he can’t bring himself to kill him (after all, it wasn’t really Ben’s fault that Dan died). As William goes to mourn his father’s death, Ben boards the 3:10 to Yuma and heads to prison. As the train leaves, Ben whistles to his horse who runs after the train...meaning that Ben will escape.
(Thanks for the update, Wendy and James)