When Environmental Protection Agency inspector Steve Malone travels to a remote military base in order to check for toxic materials, he brings his family along for the ride. After arriving at the base, his teenage daughter Marti befriends Jean Platt, daughter of the base's commander, General Platt. When people at the base begin acting strangely, Marti becomes convinced that they are slowly being replaced by plant-like aliens.

Terry Kinney
as Steve Malone

Meg Tilly
as Carol Malone

Gabrielle Anwar
as Marti Malone

Reilly Murphy
as Andy Malone

Billy Wirth
as Tim Young

Christine Elise
as Jenn Platt

R. Lee Ermey
as General Platt

Kathleen Doyle
as Mrs. Platt

Forest Whitaker
as Major Collins

G. Elvis Phillips
as Pete