Twilight was an ex-Gumshoe (private detective) named Terry Gardner who was serving his country as a Gunnery sergeant in the Marines. In his first adventure, he rescued a fortune-telling parrot which had overheard a plot to kill a foreign minister. The killers were attempting to eliminate the parrot because he was "squawking" about the plan. The parrot gave Gardner a fortune card which read, "At twilight you will be master...," leading him to don a strange animal-like outfit, complete with a "T" on the chest, from a nearby costume shop. Disguised as "Twilight," Gardner was able to capture the killers.
Twiligt possessed no superhuman powers, but was an expert fighter. He was assisted in his crimefighting efforts by the parrot from his first adventure, Snoopy.