Poseidon
In the northern Atlantic Ocean, the ocean liner Poseidon, named for the Greek god of water, is sailing through the ocean. On one of its thirteen decks, we see Dylan Johns (Josh Lucas) running for an evening workout, stopping when he reaches the top to enjoy the last sunset of 2005. Meanwhile, in one of the 800 cabins, Jen Ramsey (Emmy Rossum) is canoodling with her boyfriend/fiance Christian (Mike Vogel) when they are interrupted by Jen's father, former firefighter/mayor of New York Robert Ramsey (Kurt Russell). Christian immediately starts sucking up to the older man, who tells Christian, "Stop calling me sir....it makes me feel old." He also implies that the kids are having sex, which Jen flatly denies before stomping off to her room of the large suite. Down below in the kitchen, an attractive Spanish girl named Elena (Mia Maestro), is hunting for her friend Marco Valentin. She finds Marco (Freddy Rodriguez), a waiter on the ship, and we quickly learn that he is smuggling her across from Europe so she can be with her sick brother in New York. He gives her some food from a nearby plate, but he tells her that she has to stay in the cabin. Elsewhere, gay architect Richard Nelson (Richard Dreyfus) calling his boyfriend, but he only gets the answering machine, and we can tell that his lover recently broke up with him.
That night, Captain Michael Bradford (Andre Braugher) welcomes everyone to his ship. He tells them a little about its namesake and then introduces musical act Gloria (Stacy Ferguson). While she performs we go up a few decks, Dylan and Ramsey are playing a game of Texas Holdem with two others, generic guy five and Lucky Larry (Kevin Dillon). Jen and Christian come up to say hello to Ramsey before heading over to the nightclub as he's nearing a fifty thousand dollar betting mark with Dylan (Larry and guy five folded). Ramsey asks Jen to button up her dress to cover her breasts, and as she does says loudly for all about his hand, a pair of fives . Ramsey looks up at Dylan, who is grinning evilly and saying, "All in." Over at another table, we see Nelson telling some of his friends the story of his breakup and his ex's quick turnaround while he orders a five thousand dollar bottle of wine for the table just before excusing himself to get some air. Meanwhile, we see Dylan walking away with his winnings when he bumps into a kid playing with his PSP. The kid is Connor James (Jimmy Bennet) and he takes an immediate liking to Dylan, as does his mom Maggie (Jacinda Barret) who quickly comes up looking for him. Meanwhile, we see Jen and Chris in the nightclub partying like crazy as Elena picks her way through the crowed lower decks.
On the bridge the officer of the watch gets a feeling that "Something's off," when the instruments suddenly detect a HUGE 150-foot tall, tidal wave coming towards the ship (Nelson, who was about to jump overboard, also sees this and it ironically makes him rethink the suicide). The officer orders a hard to starboard in order to meet the wave head on, but it is too late. The wave hits the starboard side of the ship, sweeping dozens of people overboard (some of whom were in the on-deck pool), crushing others, flash-frying some, electrifying a few, and in general causing all sorts of hellish chaos. The Poseidon completely turns over, upside down and within seconds, all power on the ship goes off and the lights fail, plunging the capsized ship into darkness.
In the large dining room, after the general chaos has subsided, Captain Bradford calls for order and assures the people that as soon as the rogue wave hit the ship, a signal went off and rescue teams are on the way. As he's talking, Maggie notices Connor stuck on a piano on the ceiling (it was bolted down). Ramsey comes over and with the help of a few others creates a slide out of a curtain for Connor to fall into. In the nightclub Jen in Ok but one of the spotlight girders has fallen on Christian, trapping his leg. Jen tries to get it off but is unable to. Looking around, she spots Elena and gets her to help, and the two girls try again. Ramsey asks the captain to let him go search for Jen but the Captain wants everyone to stay put. Connor notices Dylan taking off, he explains that they can get out through the propeller area. Nelson, Ramsey, Maggie, Connor, decide to join Dylan and they grab Marco to be their guide. As they leave, we see hatches seal behind them as the captain mutters, "God be with them." On the other side, in the galley, the group picks their way through a messed up area, eventually coming to a service elevator that should lead them to safety. To cross the shaft, they grab a flimsy metal shelf and use it as a bridge. Dylan tries to get the doors on the other side open, but they won't budge. He notices the doors on the next level "up" are open, so Nelson volunteers as a stirrup to get him up there. Just as Dylan finishes getting the upper doors open, an elevator cab "above" them starts lurching "down" and it becomes a race to get everyone through. Finally it's down to Nelson and Marco. The makeshift bridg falls, and Marco grabs onto Nelson's leg. Realizing they can't save both, Dylan orders Nelson to kick Marco off, and Marco falls all the way to the bottom of the shaft before being crushed by the elevator which also falls to the bottom as well. The group recovers and heads on.
Back in the nightclub, Elena and Jen are still struggling when they are approached by Lucky Larry. He repositions the rod they're using for leverage and they are able to get the girder off of Christian just as the other group arrives. Ramsey and Jen reunite, and everybody is introduced (except for a very drunk Larry). They escape via a hot door that seems to have a fire behind it. Dylan and Ramsey open the door, Dylan reveals he used to be in the Navy, and they end up in the main concourse of the ship. They use a fallen escalator as a bridge to climb to the other side. Most of the group gets across, but when it's Lucky Larry's turn, he decides to do it without help. Just as he's in the middle, an auxiliary diesel unit comes through the ceiling(floor), killing Larry, destroying the bridge and causing a literal waterfall of burning oil. Ramsey says to find another way across, but Dylan grabs a nearby fire hose, dives into the water, swims across, and climbs up to where the others are, making a kind of bungee bridge. Ramsey still wants to find another way, but Jen is insistent on this way and shows him the ring finally. He settles, but then she ducks out and comes back with a little hook for him to hang onto. They slide across together with her piggybacking on him while he holds onto the hook, and the group heads off once more.
Back in the concert area, we see people milling around when suddenly the captain notices the glass cracking. He gets about five seconds to digest this when suddenly all the windows burst open and water comes pouring in, drowning everybody. Meanwhile, Elena, Ramsey, Nelson, Jen, Christian, Dylan, Maggie, and Connor have found a shaft that they think might lead "down" to the next level. Ramsey checks it out and says it's good, and eventually they all get in there, despite Elena's claustrophobia. While they're climbing, Ramsey congratulates Christian just as they reach the locked exit from the shaft. Ramsey tries to get his fingers around to unscrew it, but he can't so he calls up Connor to unscrew. As Connor is climbing, Nelson suddenly slips on a part of the vent that had buckled. Elena freaks out, especially since the water is rising, but Dylan manages to convince her to push Nelson out. She does so just as Connor gets the last screw out. They narrowly escape the vent, although Dylan is nearly drowned. They end up in some kind of ballast chamber, and Dylan realizes the only way out of it is to flood the chamber so the vent on one side of the room opens. They let the water in and after a while, the vent opens and they swim for some stairs. On the way though, Elena gets caught on something and manages to cut herself pretty badly. Ramsey manages to get her out of the water and tries CPR but she is drowned. The group leaves Elena's dead body behind, and moves on. The ship is slowly sinking and water levels keep rising.
Back with our remaining heroes, we see that the area they need to go get out is currently under more water than they could swim through. Discouraged, they regroup and try to think of another way out when suddenly the ship starts going vertical. They realize that this means the previous way that was blocked might now be clear, and they head that way when Maggie notices that Connor is missing. She and Dylan search for him while the others secure an exit. They find him trapped behind a screen in an area that is rapidly filling with water. Dylan dives under and tries to get him out. After a couple of attempts he frees the boy and the trio rapidly make for the other four, who have made it into the engine room. Nelson sees the door to the bow thrusters and opens it, only to get blown back by the hurricane-force winds the still-active propellor is generating. While Jen looks after him, Christian suggests throwing something in there to block the propellers and get them to stop, but Ramsey points out they'd need to either stop them manually or get them turning the other way, which makes the two argue about who should make the hundred and fifty foot swim to the underwater control room. Christian says that he has better lung capacity so he should do it, and Ramsey reluctantly agrees. Christian moves to say a teary goodbye to Jen, and while he's busy with that, Ramsey dives in and swims off. The other three arrive and are told what Ramsey is doing as we see Ramsey get in the control room. He finds the engine stop button, but it's broken. He starts running out of air, and with his last breath manages to find the button to make the propellers turn the other way.
Back in the propeller room, everyone notices that the blades are now turning the other way. Dylan tries to throw a compressed gas tank into the blades to get them to stop, but the tank gets caught crosswise in the narrow door frame. The water threatens to burst into the little room they are in and Dylan finally manages to push the tank into the thruster shaft. There's a huge explosion that blows out that pair of thrusters. The six survivors pick their way through the tube, stopping at a long drop to the water. Dylan says they have to jump, and soon everybody is in the water and swimming for a nearby liferaft. They get in just as the ship goes under, and Jen screams at them to row like crazy so they don't get drowned in the backwash. They manage to escape it. Dylan fires off a flare gun to let any rescue teams know where they are. After a wait, a pair of helicopters arrive and hover over the raft.
