Batman eventually managed to deduce Black Mask's identity, and correctly predicted that Bruce Wayne would be Sionis' next target. To set a trap for Black Mask, Bruce held a masquerade ball at Wayne Manor, and Sionis infiltrated the ball and lured Bruce to the mansion's conservatory to kill him. Bruce disarmed Sionis, forcing the latter to retreat to his hideout with Robin (Jason Todd) secretly following him. While Batman and Robin fought his underlings at the graveyard, Black Mask escaped through a false bottom installed in his father's coffin and headed to his family estate. Black Mask then entered his old bedroom and set fire to the old toys inside, intending to burn the mansion to the ground to symbolically kill his old identity as Sionis. Before Black Mask could escape, Batman flung a Batarang-attached cable around the crime lord's knees, causing him to fall face-first on the burning floor just as the bedroom's rafters began to collapse. The rafters pinned Black Mask's face into the pile of burning toys, and although Batman and Robin were able to tow him out of the fire, Sionis' mask had been burned onto his face. Black Mask was subsequently sent to Arkham Asylum, where he remained behind bars until the international terrorist Ra's al Ghul freed all of its inmates. Black Mask was not amongst the criminals who followed the Joker in searching for the one behind the breakout and thus never took part in the "war" against Batman's allies and loved ones. As this tale was the last "canonical" one to take place on Earth-One, it can be assumed that Black Mask remained at large.