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 and daughter Rebecca as hostages and Seperate them from him 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. During his rescue Damies tries to interriogated him but just winds up alerting Deathstroke's men and starting a huge brawl. While the mutagen is complete by then, Langstrom creates enough antidote to stop the Man-Bats created.