After a scan of a couple's unborn child is found to have strange growths protruding from the head and back, the foetus is taken from inside the mother by a demon creature while she is asleep. Mulder heads to investigate after Agent Spender dismisses the claims, and discovers that the father is actually a demon who wants to have a 'normal' child.

Mulder and Scully have 24 hours to save Assistant Director Skinner from being killed by a biologically engineered disease. The disease appears to be created by a shadowy government organisation but in order to save Skinner's life; they must determine who wants him dead, and why. With Skinner's condition worsening Mulder seeks assistance from Senator Matheson who he hopes can provide some answers and help him to find a cure.