Frank L Packard was an early 20th century Canadian author. Packard worked for the Canadian railroad as a civil engineer. He used his knowledge and experiences to write a series of mystery novels. He often wrote about the character Jimmie Dale. He was a wealthy playboy by day, but at night put on a costume and became The Gray Seal. He entered businesses or homes and broke into safes. Each time he left his calling card, a diamond shaped, gray paper "seal". He never took anything until a woman caught him and blackmailed him to war against certain crime organizations. The Further Adventures of Jimmie Dale is one of several books featuring the detective Jimmie Dale.