Voyagerdesperately low on fuel, finds deuterium on a highly hostile "Demon class" planet. Tom Paris estimates that they have less than a week's worth of deuterium left, even if they travel at one-quarter impulse. Captain Kathryn Janeway orders Tuvok and Chakotay to brainstorm energy conservation methods while she and Harry Kim try to synthesize an alternate fuel in the Geophysics lab.
Tuvok evacuates the crew from crew quarters and instructs them to bring only essential personal items, in the interest of conserving space. He confiscates Neelix 's copy of the Selected Works of Jirex as well as his pillows and blankets, which Neelix claims he needs because Starfleet bedding gives him neck pains and a rash. Tuvok tells Neelix to ask The Doctor for an anti-inflammatory and some anti-itch cream and Neelix grumbles that he might as well sleep in sickbay A display of the Silver Blood homeworld. Seven of Nine is still working in astrometrics despite having been ordered to shut down the lab an hour ago, due to lack of power.
Chakotay tells her that this is inefficient but Seven counters that efficiency is relative, since she has discovered a planetoid. Chakotay identifies the planetoid as Demon classtoo toxic and volatile to even enter a standard orbit. Seven responds by telling him that they are desperate and need the deuterium no matter what they have to do. Seven and En Kashimuro Nozawa try to transport deuterium from the planet but the pattern buffers overload, causing an explosion and taking the transporters offline. Tuvok estimates that if they tried to send a probe to collect the deuterium, it would incinerate upon entering the atmosphere and Janeway, discouraged and out of options, orders Paris to their course at one-quarter impulse.
Kim suggests taking a modified shuttle to the surface and mining the deuterium from there. Tuvok and Janeway object that the planetoid's atmosphere could kill him within minutes if his environmental suit corroded and that they wouldn't be able to communicate with him or transport him off the surface until the transporters were repaired.
Kim says he knows the risks and volunteers Paris to him.
After the meeting, Paris remarks on Kim's sudden attitude change. Kim says that he has realized that with all the experience he has accumulated on Voyager in the past four years, he has no reason to act "green" anymore or to be afraid to voice his opinions. Paris asks Kim to leave him out of it the next time he decides to assert himself, because he hates hot weather.
Kim and Paris land their shuttle on the planet's surface and search for the deuterium. They find a cavern with a pool of thick, metallic liquid, packed with deuterium, with other pools nearby. Paris goes to check out another one while Kim collects samples. Paris jokes about setting up some lounge chairs and a beach umbrella and having a nice vacation, and realizes that Kim isn't responding to him. He returns to the pool and finds that Kim has fallen in — Kim says he felt like he was pulled in.
The computer in Kim's environmental suit warns him that a seal has been compromised and he will be deprived of oxygen in thirty seconds. As Paris tries to get him back to the shuttle, his suit also breaches. They collapse on the planet's surface. The Doctor is not happy that Neelix and a few other officers are trying to set up makeshift quarters in sickbay.
He calls Chakotay down to complain but he is unsympathetic and threatens to shut down The Doctor's program to save power. The Doctor grudgingly tells Neelix and his friends to make themselves at home. On the bridgeJaneway and Tuvok are trying to scan for Paris and Kim, who haven't returned from the surface. Janeway isn't willing to risk sending down another shuttle and sees no alternative but to land the ship.
The landing severely damages many of the ship's systems, as well as depleting so much of their remaining fuel that they will not be able to take off again. Janeway orders repair crews sent out and sends Chakotay to look for Paris and Kim. Lieutenant B'Elanna Torres tries to get Chakotay to take her along on the search and rescue mission but Chakotay tells her that he needs cool he and that she's too personally involved. She asks him to take Seven instead. In sickbay, Neelix tries to sleep while The Doctor noisily goes about his routine.
After he threatens to start a sing-along, The Doctor allows him to turn off the lights. On the surface, Chakotay and Seven find Paris and Kim's shuttle, unoccupied. Their tricorders don't pick up any life s, so they follow the footprints instead. Chakotay falls after a cliff gives way and is barely able to keep from going completely over.
Seven grabs him but is unable to pull him up. At that moment, Paris arrives to grab Chakotay's other hand and pull him up, without his environmental suit. Paris tells Chakotay and Seven that after he and Kim passed out, they woke up able to breathe the planet's air. He invites Chakotay and Seven to take off their helmets and try it but Chakotay isn't willing to take any risks. They go to find Kim, who is further inside the cavern. Meanwhile in engineeringTorres and En Vorik try to keep Voyager 's systems running.
Vorik estimates that the transporters will be repaired within an hour but that life support will fail in two hours. Seven and Chakotay eventually find Kim in the cavern, also without his suit.
He and Paris have already collected twenty kilos of deuterium and Kim is eager to stay on the planet and keep working but Chakotay insists on returning to Voyager. As Janeway and Tuvok shut down all but two decks to try and conserve the last remaining power, Chakotay contacts them informing him of his success with finding Paris and Kim and their deuterium haul.
The Doctor, now with patients incoming, happily ejects Neelix and his other unwanted guests from sickbay to make room for Paris and Kim. The away team is beamed aboard but, surprisingly, Paris and Kim start to suffocate when they materialize in the transporter room. Janeway orders them beamed to sickbay, where The Doctor establishes a force field around two of the biobeds and fills it with the planet's atmosphere so that Paris and Kim can breathe.
In sickbay, The Doctor has found a silver fluid in Paris and Kim's blood and supposes that they have been " bioformed " to survive on the demon planet.
The Doctor doesn't know how to reverse the process and Voyager can't safely replicate the planet's atmosphere, which means that if Paris and Kim's condition can't be treated, they will have to be left behind when Voyager leaves. Janeway sends Chakotay and Seven back to the surface for more information and Kim volunteers to help them while Paris stays on the ship to play guinea pig for The Doctor.
Janeway intends to study the silver fluid with Torres in the meantime. On the surface, Seven finds the planetoid decidedly unappealing but Kim calls it "breathtaking". Where Seven sees monochromatic rocks and dust, Kim sees " a dozen shades of red and gold " and says that he feels connected to the planet.
Seven's tricorder detects humanoid life s. They immediate head for them.
They follow it through the caves and are surprised to find another Kim and Paris, now in their suits as they had collapsed before. The Kim does not seem to know. In Voyager 's science labJaneway and Torres analyze the silver fluid.
Along with deuterium and dichromatesthey discover that it has organic properties, a protein. Suddenly, the sample oozes onto Torres' thumb and, when she puts her hand back down, it creeps off her and duplicates it exactly.
Suddenly, a pool of the silver fluid forms underneath the ship and begins to sink Voyager. Janeway orders an emergency ascent and Tuvok contacts the away team to beam them back. They tell him that their party now has five members, so Janeway has them beamed directly to sickbay as a group using a wide transporter beam.
Oddly, the unsuited Kim doesn't want to leave the planet and runs away. Janeway and Tuvok try to get Voyager off the planet and back into orbit but the ship is being restrained by an electromagnetic force. When they try to compensate, the thrusters overload and go offline. Decks 14 and 15 get submerged.
The ship continues to sink and Janeway determines she needs thrusters. She calls engineering, where Vorik answers that Torres is already working on repairing the thrusters but it will take at least half an hour. Instead, Janeway orders Tuvok to work on firing on the fluid with a nadion pulse in order to disperse the fluid while she checks on Paris and Kim in sickbay.
There, The Doctor has successfully resuscitated the real Paris and Kim, but can't explain why there are two identical Parises there. Janeway offers an explanation: the silver fluid has mimetic properties. It sampled Paris and Kim's DNA and created duplicates with identical memories and personalities but with the ability to survive on the planet.