A bizarre occurrence causes Neelix and Tuvok, who are attempting to transport back to Voyager from an away mission, to arrive aboard ship as one. The crew is astonished when a strange but oddly familiar alien humanoid with dark speckled skin and pointy ears appears. The Doctor's bio-scanner shows that the Neelix and Tuvok's patterns have merged, causing the pair to become one entity — Tuvix — a humor-filled, logic-defying fusion of the two crewmen. While Tuvix assimilates and starts to become a valued member of the team, Kes struggles with the fact Neelix may not be part of her life anymore. Meanwhile, The Doctor devises a method to restore Tuvok and Neelix, except for one variable... Tuvix doesn't want to die. When the Doctor, who is programmed to follow certain ethical guidelines, cannot perform the separation, Janeway is left with a monumental decision.

Tom Wright (Tuvix)
Simon Billig (Lieutenant Hogan)
Bahni Turpin (Ensign Swinn)