Dr. Merrill (Montgomery) is kidnapped and shipped to an island far far away. Mark (Duffy) and fellow workers at the Foundation for Oceanic Research deduce where she’s being held and head into the super sub to save her.
The third TV movie leading up to the short lived series; this one, again, suffers from not enough material to stretch to feature length. There’s a bit of “Invasion of the Body Snatchers” here as the sci-fi aspect is put front and center but this seems better suited to the hour (i.e. 48 mins) long format of weekly episodes.