The Death Scouts

Directed by Mark Daniels

Written by Robert Lewin

Cast: Patrick Duffy as Mark Harris, Belinda Montgomery as Dr. Elizabeth Merrill, Tiffany Bolling as Lioa, Burr DeBenning as Xos

Released 1977

A made-for-television movie first airing on April 22, 1977 on NBC.
Three scuba divers disappear while on a dive and then two reappear changed. They have been replaced by water-dwelling aliens sent to Earth to check out its defensive capability. They believe that Mark Harris, when he tracks them down, is one of them.