Mulder is given a tip about potentially dangerous paramilitary operations on the U.S. soil but during the sting operation is surprised to find out the identity of his mysterious informant - it turns out to be Alex Krycek. Suspicious about his true motives, Mulder reluctantly follows the information provided by Krycek. However, soon he discovers a much bigger conspiracy which takes him to a gulag in Tunguska, Russia where prisoners are being used for experiments involving a substance of alien origin.

While imprisoned in Russia and infected with the Black Cancer, Mulder learns that Krycek is working with the men responsible and everything has been a setup from the start, while Scully and Skinner are called to a suspicious Senate hearing where the only question is the whereabouts of Agent Mulder.