Ace was a German Shepherd dog originally owned by an engraver named John Wilker. He was found by Batman and Robin after his master was kidnapped by a gang of counterfeiters. With his master unable to fight off the kidnappers, Wilker's dog jumped to his defense. Ace put up a savage attack but was beaten into unconsciousness by the thugs. Disoriented but determined to rescue his master, the brave canine dove into the river in search of Wilker. While on patrol that night, Robin spotted the dog struggling in the water and joined Batman in plucking the dazed animal from the river. The dog soon recovered its energy and Bruce Wayne put an ad in the newspaper, believing that someone would recognize the brown German shepherd with the distinctive diamond patch of fur on his forehead.