Sir Thomas Forsythe was the son of Lady Alice Forsythe and uncle of Captain Paul Ames. Sir Thomas was a Scotland Yard colonel who was baffled by a series of brutal killings which plagued London. Initially he chose not to believe his nephew's theory that the murders were the work of a werewolf, certain the killings were being done by a normal wolf hat had escaped the zoo.
Dr. Yogami came to Colonel Forsythe's office, telling him and Paul of the mariphasa plant in the possession of Dr. Wilfred Glendon and its usefulness as an antidote for lycanthropy, but Forsythe shrugged him off. It wasn't until he and his men found withered mariphasa blossums in Yogami's apartment, the site of a third murder, that the colonel finally put two and two together. Forsythe and his men drove to Glendon Manor, arriving in time to shoot the lycanthropic Glendon before he could kill his own wife, Lisa.