When several black men turn up dead – their bodies completely devoid of skin pigmentation – Mulder and Scully hunt down an African killer who must consume human hormones to survive.
Scully learns new details about her sister's murder as Mulder pursues the shapeless alien entity inside Krycek's body.
The agents uncover more information in the government's attempt to hide the truth about extraterrestrial life when Mulder discovers a video of an alleged alien autopsy.
Mulder finds himself trapped on a speeding train with a government assassin, a ticking time bomb and a deadly virus.
To save his dying mother, Mulder must protect the extraterrestrial healer, Jeremiah Smith, from a ruthless alien bounty hunter.