Searching for deposits of refinable dilithium, Voyager stops off at a moon, where Chakotay, Kim and Neelix beam to the surface. It turns out that this moon is not uninhabited. A group of aliens there seem to have left a dilithium trail, and one of them attacks Neelix. When the others come to his aid, Neelix's lungs have been removed, and only some innovative but risky gambles taken by Voyager's holographic doctor can keep him barely alive. The aliens flee the moon in their own ship, and Janeway orders a pursuit. It turns out that the attackers are simply trying to survive themselves, their species all but wiped out by a deadly disease. Their only hope for survival is to take working organs from others - and they cannot return to lungs to Neelix, for they have already been used.
