Having just picked up 18 corpses with no visible cause of death from a cargo ship, the Mys Venezia, the whole gang is aboard a 737, flying into a storm. Nigel thinks it's aliens or pirates that are the cause of the deaths, but all speculation ends when co-pilot Dave Rosso tells everyone to buckle up, because they have to fly into the storm. When the engines blow out, the hatch blows off, and the plane starts to dive, Dave tells everyone to brace for the inevitable crash.Jordan stirs, then wakes Woody. Nigel's arm is injured, and two FBI Agents are missing. The pilot is dead, but Dave has survived with only a leg injury. The plane has crashed in three pieces somewhere in the snowy White Mountains, hundreds of miles off course. The radio is out and there's no cell reception, but the plane had an emergency locater transmitter, now lost. The chance of survival is looking pretty slim. Ever the boy scout, Woody begins to patch up the fuselage to keep everyone warm, putting the corpses outside to keep them cold.Flashback to yesterday, Kate is heading up the disaster response team, or DMORT, to respond to the Mys Venezia. The ship was picked up off the coast of Nova Scotia, with only two survivors on board. Kate sends Jordan to do trace on the survivors at Boston General. With Garret about to leave for a Tuscan vacation, Jordan wonders why she's not in charge of the DMORT. She hates running things, but why didn't Garret have the guts to tell her that he chose Kate instead?Jordan arrives at Boston General just as one of the survivors, who appears to have a gunshot wound to the forehead expires. The doctors have no idea what killed him or the others, but the second survivor, first mate Basit Bakar is failing fast. He keeps saying "We have to stop them," in Malaysian.Night falls, and everyone settles into the plane. Nigel feels left out as Dave tells Bug about his four-year-old son, who wants to be a pilot, too. Bug flashes back to yesterday, when he was making Madeleine smile, while Nigel ponders the mystery of the dead crew. Bakar is now dead, and Kate informs that they'll all be leaving for the ship with the DMORT team in four hours. Bug doesn't want to go - now he has Madeleine to think about - but Nigel guilts him into it.In the morning, Woody wakes Jordan. Dave must have gotten up to check on the fire and frozen to death. Everyone says something nice at Dave's burial service, except Kate. She freaks out, blaming Dave for the crash, and wondering who will die next. Bug vows they'll get out of there, if only to tell Dave's son how their father saved them.The gang pools their food and water, and there's not much to share. Kate apologizes to Garret for her outburst, offering to be food monitor. It will be easier, since everyone already hates her anyway. While checking the corpses for food, Jordan identifies one body as the ship's engineer, Hamberi. He's got ammonium nitrate on his boots and his hands smell of diesel fuel - this guy was making a bomb!While looking for dry wood Nigel insults Bug, telling him he's talking about Madeleine too much. They stumble over the frozen corpse of one of the FBI Agents, only to find the emergency locater transmitter - with a big hole in it. Apologizing to Bug, Nigel resolves to fix it, using the amplifiers from their cell phones.Garret gets the rest of the gang to start trace on the bodies. Thirteen crewmen were found locked up - they were starved and deprived of water. The five others, including navigator Kim, appear to be hijackers. Looking through their effects, Garret finds a schematic for the Charlestown Bridge, and Kate pulls up a flyer advertising a big parade. Suddenly, Garret passes out. Turns out he's got internal bleeding from a broken rib which has lacerated his spleen. Jordan applies a pressure bandage, which should buy him a few hours, if he keeps still.Woody wants to hike up the mountain to set off the emergency locater, and Bug volunteers to go with him. Kate tries to go in Bug's place, saying that he should think of Madeleine, and not endanger himself. Bug claims that Madeleine is the reason he's going. Jordan finds Garret working. He admits that the reason he didn't put her in charge is that she should never be in charge. She's an agitator, and Garret needs her to push him and the team to be their best.Garret collapses on Kim's corpse, pushing an odor of vapor rub out of his lungs. Jordan realizes this is what killed the crew - deadly soman gas. The hijackers were going to set off a dirty bomb, wreaking havoc on Boston - but why release it in the middle of the ocean? Meanwhile, Woody and Bug reach a sheer wall of rock - there's no way to get to the mountaintop. Bug decides to activate the transmitter anyway, in hopes of saving Garret, but it dies.Jordan and Garret puzzle over the case. The hijackers must have boarded the ship and locked up the entire crew, except for Bakar and Kim, who were needed to pilot the ship. Realizing the hijackers plan, Kim sacrificed the lives of the crew and himself to set off the dirty bomb at sea, thus saving the lives of thousands, just like United Flight #93.Nigel is overjoyed when Woody and Bug return, until they admit that the transmitter died. Facing the fact that they might die, everyone retreats to think it over. Finally, Jordan confesses to Woody that she loves him. She's not asking for anything, she just didn't want to leave it unsaid. As they share a deep kiss, the beating of helicopter blades can be heard overhead.The gang celebrates with hugs while Jordan runs to Garret, who tearfully thanks her for coming back from L.A. when he needed her. Series Finale.