Tuvok's brain damage leaves him unable to function.
After a diplomatic mission, Tuvok is attacked by an invisible alien aboard a shuttle and suffers brain damage, losing most of his memory and Vulcan control. A local investigator helps Voyager search for the mysterious Ba'Neth, a cloaked race whose existence few believe in, while Neelix devotes himself to helping Tuvok recover.
Free of his usual discipline, Tuvok becomes warm and curious, enjoys jazz and discovers a talent for baking, and he and Neelix form a real friendship. The crew need Tuvok's buried memories to find the Ba'Neth, and he finally recalls their cloaking frequency, drawing it in icing on a cake he has made. The crew expose the alien station and obtain the information needed to treat Tuvok, and he returns to his old self, though he keeps a small trace of his new personality. The sixth-season episode is a gentle study of Tuvok and Neelix's long odd-couple relationship.