Extinction

Enterprise visits a jungle planet that the Xindi recently explored. Archer, Hoshi and Reed are infected by a mutagenic virus that transforms them into members of an alien species, the Loque'eque. T'Pol, also exposed, proves partly resistant thanks to her Vulcan physiology. Changed in body and mind, the three feel an instinctive compulsion to reach a city called Urquat, and vanish into the planet's ruins. Two containment ships arrive and demand access to the infected. Their leader, Tret, explains that the virus devastated his people sixty years earlier, and that they are determined to contain it. He reveals that the Loque'eque created the virus as a last attempt to survive their own extinction. The transformed crew members are recovered, and Phlox synthesises a cure using T'Pol's genetic material. Once they are restored, Archer asks Phlox to keep the last sample of the virus, the only remnant of a vanished civilisation.