S2E19 · Død Kalm

In the Norwegian Sea, chaos erupts on board USS Ardent, an American destroyer escort. Due to mysterious and unspecified events, half of Ardent' s crew board lifeboats and abandon ship against the captain's orders. Eighteen hours later, they are spotted by a Canadian fishing vessel; however, in that short span of time, the young crew members have undergone rapid aging.

Dana Scully (Gillian Anderson) is asked by Fox Mulder (David Duchovny) to visit the ship's sole surviving crew member, Lt. Harper, who has been quarantined at the Bethesda Naval Hospital. She finds that Harper, despite being in his twenties, has inexplicably aged to the point of being unrecognizable before she is escorted from the room. Mulder explains that Ardent vanished at the 65th parallel, a location with a history of ship disappearances. Mulder believes that a "wrinkle in time" exists there, and that Ardent was the subject of government experimentation related to the Philadelphia Experiment from World War II.

In Norway, Mulder and Scully hire Henry Trondheim (John Savage), a naval trawler captain, to take them to Ardent' s last known location. After crashing into the bow of Ardent, Mulder, Scully and Trondheim find signs of advanced corrosion, even though the warship is only a few years old. Below decks, the party finds the mummified remains of several crew members. They also find the wizened commanding officer of Ardent, Captain Barclay, who claims that "time got lost" after his ship encountered a "glowing light" in the ocean. Trondheim's boat is stolen, and his first mate is murdered.

Trondheim is attacked by a Norwegian pirate whaler named Olafsson, who has not aged despite being on the ship for the past two days. Mulder, Scully and Trondheim eventually begin to age unnaturally. Scully develops a theory that Ardent is sailing near a metallic object beneath the ocean, and that it has caused free radicals to rapidly oxidize their bodies. When Mulder notices that the ship's sewage pipe is the only one not corroded through, the agents realize that something from the ocean contaminated Ardent ' s potable water and led to the aging; Olafsson and his men remained unaffected due to their consumption of recycled water from the sewage system. Desperate to survive, Trondheim kills Olafsson after he reveals the secret and sets out to keep the water for himself.

Scully learns from blood tests that the contaminated water causes rapid oxidative damage and dramatically increases sodium chloride in the body. She tries to ration the drinkable water amongst the three but discovers Trondheim attempting to hoard what little that remains. Trondheim locks himself in the sewage hold, forcing Scully to use minuscule supplies to keep Mulder alive. The mysterious oxidant eventually eats through Ardent ' s hull, flooding the sewage hold and drowning Trondheim. The agents both lose consciousness shortly before Navy rescuers arrive at the ship. Scully comes to at the hospital, where she is told that her written observations on the case helped naval doctors reverse their aging and save Mulder from near-certain death. Scully says that she wants to return to Ardent for more research, but the doctor tells her that the ship sank shortly after their rescue due to the flooding.