On stardate 49655.2, Lieutenant Commander Tuvok (Tim Russ) and Neelix (Ethan Phillips) are sent to collect botanical samples from a class-M planet. When beamed back aboard , the two men and the Orchidaceae they collected are merged at the molecular level to become a single lifeform which names himself Tuvix (Wright). After ruling out transporter malfunction, the crew discovers that when demolecularized, the genetic material of the alien orchids acted as a symbiogenetic catalyst and is the culprit for the combination of the two crewmembers. Unfortunately, the process cannot be reversed, and Tuvix is accepted as a member of the crew with the rank of lieutenant, functioning as chief tactical officer in Tuvok's stead.