At the beginning, he works for Ra's al Ghul in an attempt to create an army of Man-Bats to strengthen the League of Assassins. Kirk Langstrom was also behind the mutagen that Killer Croc empowered himself with where he had sprouted a tail. After Ra's al Ghul's death, Deathstroke recruits him to continue his work. This time, Deathstroke takes his wife Francine (voiced by Diane Michelle) and daughter Rebecca (voiced by Kari Wahlgren) as hostages so that Langstrom can create the Man-Bat Formulas. When Batman finds a lead in Kirk Langstrom's lab, he is attacked by a mutated ape that was living there. All three are later rescued by Batman and Damian Wayne. While the mutagen is complete by then, Langstrom creates enough antidote to stop the Man-Bats created. The Man-Bats don't seem to be covered by the Thou Shalt Not Kill rule. Batman takes no issue with Damien using a sword on them, and he himself crushes many of them with falling debris set off by explosives.