Writer/director Curtis Harrington does an admirable job working around the severe budget limitations of the 1963 psychological chiller Night Tide. Sailor Johnny (Dennis Hopper) falls in love with carnival-girl Mora (Linda Lawson), despite warnings that Mora is a "jinx" who has brought about the deaths of two previous suitors. Mora performs a mermaid act at the carnival, but to her it's no act: she believes herself the descendant of an underwater race that must kill by the light of the full moon to survive. One evening, Mora tries to kill Johnny, prompting his quick exit. He returns some time later to discover, all too late, that the film's real villain is the jealous carney owner (Gavin Muir).
~ Hal Erickson, All Movie Guide