"It's a Boy" stars Horton as Dudley Leake, who is betrothed to Mary Bogle (the very pretty Wendy Barrie). Shortly before the wedding, Dudley blurts a confession to his friend and best man, Jim Skippett: 20 years ago, Dudley had a brief affair with a certain Miss Piper, but he's never heard from her since then. Next day, who should suddenly appear? A youth about 19 or 20 years old, claiming to be named Joe Piper. Is he Horton's son, or is Skippett playing a practical joke?
James Skippett
Joe Piper
Dudley Leake
Anita Gunn
Eustace Bogle
Allister
Mary Bogle
Mrs. Bogle
Lillian
Registrar
Inspector Burns
Publisher
Bride at Registrar's Office
George
Director
Screenplay
Screenplay
Scenario Writer
Scenario Writer
Screenplay
Producer
Production Assistant
Director of Photography
Editor
Art Direction
Costume Design
Unit Production Manager
Sound Recordist
Music Director