Archer, Reed and Hoshi are exposed to a highly contagious virus that transforms their bodies, minds and memories into those of long-extinct aliens from a tropical world.
A lonely telepath begs Hoshi to visit his faraway planet in exchange for information on the Xindi, then refuses to allow the linguist to leave.
When Mike is lethally poisoned, he has to fake the assassination of a billionaire tech mogul in order to get the antidote; a mysterious woman from Mike's past returns.