 Jan Letterman (Barbara Wilkin), the personal assistant to a wealthy, over-the-hill actress named Laura Winters (Rita Morely), hires pilot Grant Murdoch (Byron Sanders) to fly her from New York to Provincetown on Cape Cod in Massachusetts, but a storm forces them to land on a small island.They soon meet Prof. Peter Bartell (Martin Kosleck) a marine biologist with a German accent who is living in seclusion on the isle.After a series of strange skeletons wash ashore (human, then fish) it turns out the water has become inhabited by some sort of glowing microbe which apparently devours flesh rapaciously.