Synopsis by Hal Erickson
Doggett (Robert Patrick) reluctantly agrees to join forces with his predecessor, Mulder (David Duchovny), to solve a series of deaths on an oil rigger in the Gulf of Mexico. Despite the pooh-poohing of the Galpax Petroleum executives, Mulder is certain that the malevolent black oil alien virus is responsible for the deaths. In the course of the action, Mulder and Doggett are both trapped on the quarantined rig. Elements crucial to the plotline include the curious immunity of one of the oil workers and a revelation made by Mulder at the end of the episode. "Vienen" (the title translates from Spanish as "They Come") first aired on April 28, 2001.