Philip Macdonald
Philip Macdonald was the grandson of the writer George MacDonald. During World War I he served with the British cavalry in Mesopotamia. He later trained horses for the army, was a show jumper, and moved to Hollywood in 1931. He was one of the most popular mystery writers of the 1930s, and wrote over 25 novels. Fifteen film adaptations were made of his novels, and he also wrote many screenplays.