The movie begins with Pierce Bronson at a Lakers Game. There are FBI Agents all around keeping an eye on him. At the same time we see Woody Harrelson in a SUV with a briefcase containing a diamond. When they stop in traffic, a bum attempts to clean the windshield and all Woody gives him is a dollar. Next, they cut back to the Lakers game and a fan gets out of hand. Suddenly, the FBI can't find Pierce. You see Pierce leaving the arena and as he's leaving he gives a VHS tape to an usher. Finally the FBI see Bronson on the jumbo-tron but can't get an actual visual. Woody starts to get nervous. Then they cut to the roof of the stadium and Pierce has a remote control. As all the other agents leave the SUV, Woody is trapped inside and can't steer the car. Pierce is steering it with the remote control. We cut back to the bum cleaning the windshield and it's actually scanning the car. Next, Selma Hayek emerges from the bum outfit and meets up with Pierce. They get Woody into an isolated location and gas him until he passes out. Just as Woody's passing out, he fires a shot off through the vent (the SUV has bullet-proof glass) and nicks Pierce in the shoulder.
Then we cut to 6 months later on some incredibly beautiful island. Selma is enjoying their retirement but you can tell Pierce is bored. One afternoon Pierce comes back to the house to find Woody sitting in his living room. Woody pulls out a brochure for a cruise ship that will be carrying the last of the 3 Napoleon diamonds that hasn't been stolen (allegedly by Pierce as he points out). When Woody leaves, Pierce searches for bugs in the house and when Selma gets back she realizes he found the bullet that hit Pierce in the last robbery. It's the only physical evidence that links Pierce to the heist. To retrieve the bullet, they pay for Woody to get the most expensive suite at his hotel and send him two hot female masseurs. Later that night one of the women returns the bullet to Selma. When Woody comes down they sick a female local cop on him for carrying a concealed weapon and he gets hauled down to the station.
Selma is also worried about the diamond on the cruise ship. She catches him taking a peak out it but he swears he isn't going to steal it. He also promises to write his wedding vows (apparently at some point they plan to marry but it's not really discussed).
At the station, he explains why he's there and the female cop (Naomie Harris) decides its a great career move for her to help him so they agree to team up. There is clear sexual tension between them. (Naomie is just dying to bust the local gangster (Don Cheadle) that everyone on the island seems to think is a gift from God).
Pierce is approached by Don to help him steal the diamond. Pierce says he's retired but is still intrigued. Meanwhile, Woody wants to question Pierce so he says he'll either drag him to the police station or they can go fishing together. Pierce opts for fishing and they sail off. They end up getting totally drunk and catching a mini-shark. It's alive when they pull it on the ship so Woody shoots the crap out of it (it's pretty funny). When they return, Selma and Naomie are surprised they are getting along so well.
Pierce continues to scope out the ship and the prospect of stealing the diamond while Selma grows suspicious. Pierce ends up sneaking onto the ship and getting copies of the blue prints. Just as he's trying to escape, the ship's captain is notified of someone breaking in and Woody and Naomie set out to catch Pierce. Woody gets in Naomies way and Pierce gets away. When he gets home Selma wants to know if he was on the ship and he says he was home all night working on his vows. At the same time, Woody and Naomie return to the room and end up having sex.
Pierce delivers the blue prints to Don and tells him which lines to cut so the cameras will be cut. Then Don reneges on any partnership agreement and Pierce leaves.
Pierce then gets a call from the bar they are always out that some guy is shouting his name and is totally drunk. Pierce arrives and gets Woody to calm down. He and the bartender take Woody to his room and Pierce actually tucks him in. When Pierce returns home he finds out that Selma looked at his notebook and he did not write any vows. She kicks him out. Pierce doesn't have anywhere to go so he goes to Woody's room (since he's paying for it) and they end up in bed together. That morning, some FBI agents from earlier in the movie show up with Naomie and another local cop (Noamie's ex-husband) and everyone finds out that Woody was on leave from the FBI and there is no operation. Naomie is mad because she thinks he was just using her.
Pierce and Woody decide they will talk to the other's woman in order to straighten out their relationships. It all works out and Pierce takes them all scuba diving. They are supposed to be looking for treasure. Pierce ends up leaving the group and another scuba diver pretends to be him. Meanwhile, Pierce heads for the cruise ship. We see a guy go in the room next to the diamond and cut a cord. He is seen on the monitors and the crew go after him. It turns out to be one of Don's guys and then we see Pierce above the diamond retrieving it. Finally the crew sees the diamond gone but it's too late.
Pierce heads back to the divers and Selma starts to realize what is happening. Just as Woody is about the grab the other diver (it's the bartender from earlier), Selma messes up his oxygen and Pierce makes it back. Once back on land they hear about the diamond being stolen and everyone knows Pierce did it. Woody and Naomie leave and Selma says she's leaving him.
When they get back to the house, Don is there with a gun and threatens Selma and Pierce. Just as he's about to kill them Woody and Naomie come in and kill him. The police then believe Don stole the diamond and was wanting to tie all loose ends. Pierce admits he was approached about stealing the diamond but denies involvement. Woody doesn't believe it but just leaves anyway.
Selma packs and leaves Pierce and he wonders off to the bar. Woody is there and basically reveals that he played Pierce the whole time about getting the idea of stealing the diamond in his head. He faked being drunk that one night and actually followed Pierce and learned where he would hide diamond. Woody now has the diamond and he believes he's finally won.
The next day Selma is about to get on the plane and Pierce stops her with wonderful vows and a promise that he is really retired.
Cut to the next day, Woody is in a limo, making a deal to sell the diamond. All of a sudden, the doors lock and the limo drives on it's own. Then you see Pierce with a remote control and he promises this is the last time.