The Invaders

Based on the TV series from the 1960s of the same name.

Earth has been besieged by clever aliens who, after inhabiting a human body, become an environmentalist's worst nightmare: they live off carbon monoxide, smoke incessantly, love car fumes, and even murder ecologists. Nolan, a handsome, strapping everyman, has just been released from prison, but is soon framed for the murder of a doctor who was aware of the aliens' presence. Nolan teams up with the dead medic's fiancee to investigate the matter. Together, they are in a race against time, with David's life - and Earth's future - at stake.