Nothing But the Truth by Frederic Stewart Isham

A young man, finding himself unexpectedly impecunious, attempts to improve his fortunes by wagering that he can speak nothing but the absolute truth for three weeks. He soon learns, however, that telling only the unvarnished truth can have surprising consequences. This 1914 novel of love, mystery, and misunderstandings, with amusing characters and plot twists, was adapted as a Broadway play in 1916, followed by six motion pictures: in 1920 and 1929; in 1931 separately in Spanish, French and German; and in 1941 starring Bob Hope and Paulette Goddard. Frederic S. Isham was a writer of short stories, novels and plays. (Lee Smalley)