Jack DeVries (Chris Mulkey), a quiet citizen with no criminal past, robs a Los Angeles Wells Fargo bank, kills all of the security guards inside, and leads the Los Angeles Police Department on a high-speed chase. The chase ends when DeVries encounters a police blockade overseen by detective Thomas Beck (Michael Nouri). DeVries is shot several times, smashes through the blockade and crashes the Ferrari he is driving. DeVries is taken to a hospital, where a doctor informs Beck and his partner, Det. Cliff Willis (Ed O’Ross) that DeVries is not expected to survive the night.

Upon his return to LAPD headquarters, Beck and his supervisor, Lt. John Masterson (Clarence Felder), meet FBI Special Agent Lloyd Gallagher (Kyle MacLachlan), who informs them that Beck has been assigned to work with Gallagher to track down DeVries. When told of DeVries’s condition, Gallagher rushes off to the hospital.

Meanwhile, at the hospital, DeVries suddenly awakens. Disconnecting his life-support equipment, he approaches the comatose man in the next bed, Jonathan P. Miller (William Boyett). After DeVries forces Miller’s mouth open, a slug-like alien emerges from DeVries’ mouth and transfers itself into Miller’s body. Gallagher arrives to find DeVries dead on the floor and Miller’s bed abandoned…