A human scientist capable of living underwater discovers similar alien life inhabiting human bodies, and looks to them for a clue to his origin.

Patrick Duffy
Mark Harris

Belinda Montgomery
Dr. Elizabeth Merrill

Kenneth Tigar
Dr. Miller Simon

Alan Fudge
C.W. Crawford

Tiffany Bolling
Lioa / Dilly

Annette Charles
Ginny Mendoza

Burr DeBenning
Xos / Chazz
Stanley Bennett Clay
Boy

Alan Mandell
Grant Stockwood
Hank Stohl
Sub Captain Wes

Russell Arms
Medical Examiner
Arch Archambault
Second Officer
Michael J. London
Air Lock Man
Vince Deadrick Sr.
Herb Wayland
Maurice Hill
Lou