During an encounter between the U.S.S. Voyager and a Nasari ship, Kim announces that the alien ship is going to fire, and he unleashes Voyager's phasers at it, triggering an unwanted battle. As both ships limp away from the confrontation, Janeway grills Kim, who says he just "knew" the Nasari posed a threat, despite their non-aggressive behavior. The Captain suspends Kim from duty until she can investigate his "hunch." That evening, Kim is stunned by the appearance of alien markings on his face.
The Doctor can't find a reason for Kim's facial markings or the alteration in his blood chemistry. Tuvok is able to confirm that the Nasari were about to fire on Voyager, and the Captain questions how Kim knew. He isn't sure, but he notes that this area of space seems oddly familiar. Kim leads the crew to the planet Taresia, which has a largely female populace. An official of that planet welcomes Kim "home."
The Taresians explain that Kim was conceived on their world, but his embryo was implanted in an Earth woman, to bring an infusion of new genetic material back to their race. As an adult, Taresians like Kim are instinctively drawn back home. The women say the Nasari fired on Voyager because they detected Kim's presence. The Nasari hate Taresians and were trying to stop Kim from going home. Later, Janeway meets with the Nasari, who say they have no quarrel with Voyager — but they'll attack the ship if Kim returns to it.
As Kim attends the wedding of Taymon, another returned male, the Doctor informs Janeway that Kim wasn't born with Taresian DNA; he was deliberately infused with it during an Away Mission. Apparently, the Taresians want to make him feel like he belongs on their world. But Kim has decided he wants to return to his ship. When he tries to leave, the Taresian women try to stop him. He races to Taymon's room, where he's stunned to find the young man's dead body. Kim realizes that Taresian men don't voluntarily leave; they're killed after the women extract enough genetic material to conceive children. The crew is able to beam up Kim and leave the area while the Nasari are busy trading shots with the Taresians.