Sub-Commander T'Pol, Lieutenant Reed and Ensign Sato are stranded on a Klingon vessel sinking into a gas giant. Captain Archer tries to convince a captured Klingon to help before the away team is crushed by the intense pressure of the planet's atmosphere.
After Enterprise drops out of warp near a gas giant, the crew detects an unexpected power signature and bio-signs in its lower atmosphere. Sub-Commander T'Pol, Lieutenant Reed and Ensign Sato take a shuttle to investigate and discover a Klingon vessel, Somraw, close to being crushed by the planet's atmosphere. On board, T'Pol finds three dying Klingons on the bridge, and further scans detect residual elements of a carbon dioxide-based neurotoxin. Bu'kaH, a surviving Klingon crewmember, escapes in the away team's shuttlepod. Enterprise traps it, but not before she broadcasts a distress signal. They then attempt to descend to rescue the away-team, but the pressure is too high.
Meanwhile, Sato finds the captain's log, which states that the ship was damaged in a skirmish with the Xarantine, and that the Klingon captain ordered his ship into the gas giant's atmosphere to effect repairs. Sato also locates the port fusion-injector on a schematic, and the away team make their way to Engineering to attempt repairs. On board Enterprise, Captain Archer talks to Bu'kaH in Sickbay. Doctor Phlox learns that the toxin was bonded to a molecule in Xarantine ale, which Bu'kaH confirms was part of their spoils. He convinces her to help them, citing the dishonourable deaths of her crew-mates.
On the Somraw, Reed uses shock-waves from photon torpedoes in an attempt to raise the ship and lower the hull-pressure. This allows Archer and Bu'kaH, in a reinforced shuttlepod, to reach them. Archer tells Bu'kaH that his team risked their lives for her ship, and that they are not leaving until it is safe. Archer arrives back on Enterprise just as the recovered Somraw hails. The now-revived captain orders Archer to surrender as punishment for violating his ship. Archer faces him down, noting that his ship is damaged and freshly out of torpedoes. Powerless to argue, the Klingon snarls and quickly ends the transmission.