Mary Had a Little is a comedy about a theater producer, Scott Raymond (Jack Watling), who hears a psychiatrist, Dr. Malcolm Nettle (John Bentley) boast that he can create the perfect child by hypnotizing a pregnant woman. Scott makes a bet with Malcolm that it can't be done. To ensure that he wins, Jack convinces an actress to pretend she is pregnant. Much to Jack's dismay, the actress falls in love with Malcolm, and she isn't happy that her new boyfriend's theories are such a laughing matter. She decides to get pregnant for real so Malcolm can prove his theory. On a drunken whim she goes to Scott's house and demands he take her. Malcolm shows up as well as Scott's girlfriend and the four spend the evening sorting out the details of this mess. Will the couple decide to get married and test the theory out for themselves? Find out in this amusing movie.