As told to a psychiatrist Mr       Peabody, middle-aged Bostonian on vacation with his wife in the Caribbean, hears mysterious, wordless singing on an uninhabited rock in the bay       Fishing in the vicinity, he catches                  a mermaid       He takes her home and, though she has no spoken language, falls in love with her       Of course, his wife won't believe that thing in the bathtub is anything but a large fish       Predictable complications follow in rather tame fashion