"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?
as James Skippett
as Joe Piper
as Dudley Leake
as Anita Gunn
as Eustace Bogle
as Allister
as Mary Bogle
as Mrs. Bogle
as Lillian
as Registrar
as Inspector Burns
as Publisher
as Bride at Registrar's Office
as George