In this 1948 movie, Arthur Peabody (William Powell) and his wife, Polly (Irene Hervey), are vacationing in the Caribbean when their marriage hits the rocks. Polly starts to admit her feelings for someone else after thinking her husband is cheating. It turns out, Arthur followed a siren song to a mermaid (played by Ann Blyth) deep in the depths of a cave. Though she cannot speak to him, he finds himself drawn to her more and more. Arthur winds up getting caught in a love triangle that makes him question his marriage and whether or not he can truly be with a mermaid.