Neelix is aghast when a Haakonian named Ma'Bor Jetrel contacts the USS Voyager and asks to meet him. The Haakonians had fought a long, destructive war against his people 15 years earlier. Jetrel is the scientist who helped them conquer Talax by developing the Metreon Cascade, a superweapon that killed over 300,000 people on Talax's moon Rinax, including Neelix's family. But now Jetrel says he has come forward to examine Talaxians like Neelix who helped evacuate survivors from Rinax, in the process exposing themselves to high concentrations of metreon isotopes. Although he considers Jetrel a monster, Neelix agrees to be examined, and is informed that he also has the fatal blood disease. Later, Jetrel convinces Janeway to make a detour to the Talaxian system. Using the ship's transporter systems, Jetrel feels he would be able to develop a cure by retrieving samples of the Metreon cloud still surrounding Rinax.
Janeway agrees, but Neelix is still bitter. He angrily condemns Jetrel for the devastation he's caused, only to learn that the scientist is also paying the price — his wife left him in the wake of the attack on Rinax, his children refuse to acknowledge him (viewing him as a genocidal monster), and he not only has the disease himself, but is in the final stages of metremia with only a few days to live. The ship's arrival at Rinax opens old wounds for Neelix. He confesses to Kes that he lied for years about being part of the Talaxian defense forces. He never reported for duty; instead, he spent the war hiding on Talax. Later, Neelix seeks out Jetrel, only to find the Doctor deactivated and Jetrel covertly conducting experiments in the lab. Suspecting the worst of Jetrel, Neelix tries to notify Janeway, but the scientist renders him unconscious.
Jetrel heads for the transporter room, where he is confronted by the Captain. Jetrel pleads with Janeway to let him conclude his work and bring back the deceased Talaxian victims of Rinax. He believes that he can use the transporter to regenerate their dissociated remains, and confesses he came to Voyager as a pretext to use the ship's transporter; Neelix was falsely diagnosed and is fine. Janeway allows Jetrel to proceed, but the improbable experiment fails. The scientist collapses, knowing that he will never be able to redeem himself. Neelix pays a last visit to Jetrel and tells him that he is forgiven, allowing the Haakonian to die with some semblance of peace.