Hoshi's target practice with Reed is interrupted when Enterprise drops out of warp to investigate a Class-9 gas giant. A probe is launched into the planet's massive atmosphere and to the crew's surprise, it detects a disabled alien vessel with several bio-signs aboard. T'Pol, Reed and Hoshi are dispatched in a shuttlepod to investigate.
When they board the "shipwreck," Hoshi recognizes the writing on the bulkhead — it's Klingon. They immediately draw their weapons and search for the survivors. Entering the dark, spooky bridge, they find several unconscious Klingons. T'Pol recommends leaving before they come to, because the Klingons would kill them rather than face the dishonor of being rescued. But Reed refuses to leave without helping. When they contact Enterprise, Archer decides to give them 20 minutes to see what they can do, because in about half an hour they'll sink to a point where the atmospheric pressure will exceed the shuttlepod's tolerance. Soon after, though, the boarding party is ambushed by a Klingon woman who managed to escape unconsciousness. The Klingon then bolts for the airlock hatch and escapes in the shuttlepod, stranding the three crewmen on the doomed vessel.
The bridge crew sees the shuttlepod approach, and upon hailing it they hear a Klingon voice. The woman, Bu'kaH, is calling her people for warships, declaring that Enterprise has attacked them. Enterprise captures the shuttlepod with the grappler and brings it aboard. Bu'kaH won't be taken easily, though — she puts up a fierce struggle before being knocked out by a phase-pistol. Meanwhile the stranded party decides their only course of action is to restart the Klingon ship's engines and pilot it out. However, using Hoshi's linguistic skills to read the instruments, they realize they're dead in the water. And Archer's plan to bring Enterprise down for a rescue hits a snag when the shipwreck falls to a depth even the starship can't withstand.
In Sickbay, where Bu'kaH is now awake but restrained, Dr. Phlox determines there's a neurotoxin in her bloodstream that will kill her in a day or two. Apparently she escaped unconsciousness because she hid in a cold place on her ship, delaying the effects of the toxin. Archer asks Bu'kaH for her guidance in getting her ship restarted, but the belligerent Klingon accuses him of raiding her vessel and poisoning her crew. Meanwhile Mayweather and Tucker search the Vulcan database and learn the Klingon ship is a Raptor-class scout vessel — it has a very thick hull, but it won't hold up forever under the pressure it's in. Tucker has the idea to reinforce a shuttlepod with duratanium braces in order to mount a rescue. Archer puts him on the task while telling Mayweather to keep an eye out for other Klingon ships. On the Raptor, Hoshi finds a log entry from the ship's captain, which reveals the Klingon crew was fighting a race called the Xarantines and hid in the gas giant to make repairs but the captain did not know why the crew was falling ill. The team also learns the port fusion injector is damaged, so they set out to find engineering. As Reed works there, he becomes dehydrated. Hoshi and T'Pol look for the galley to find water, but instead come across live targs and other Klingon food including a delicacy of live worms called gagh. As Hoshi's anxiety rises, T'Pol takes her hand and guides her through a mental exercise that calms her down. But then the ship shudders as the hull begins to buckle.
Running out of time, Hoshi suggests trying the weapons, and Reed concurs. Meanwhile Archer approaches Bu'kaH again, this time using some Klingon reverse psychology. After informing her that her crew was infected by a toxin in the Xarantine ale they drank—part of the spoils of a raid—he convinces her that she would be letting her crew die a very dishonorable death if she didn't cooperate. She reluctantly lets him take her on the reinforced shuttlepod toward her ship, along with an antidote to the neurotoxin. On the Raptor, Reed is launching the ship's torpedoes one or two at a time in an attempt to stop its descent, but not having much success until Hoshi bravely proposes they fire all remaining six torpedoes at once. The risky tactic works—the ship takes damage, but the shockwave pushes it to a tolerable altitude. Archer and Bu'kaH board the Raptor and he coerces her to work with his crewman until the engines are fixed. The job is done just in time for Archer's team to return to Enterprise before two more Klingon ships arrive. They get a hail from the recuperated Klingon captain, but instead of saying thank you, he orders them to surrender. Archer faces him down, pointing out his ship is weakened and he's fresh out of torpedoes, and he better take what honor he has left and go home. The Klingon obstinately relents. T'Pol, Hoshi and Reed now get to relax in the decon chamber, happy to be away from the smell of a Klingon vessel.