

Eventually, however, his instability returns and he is left unable to control his transformations. He works for a while as a detective and independent crime fighter as Man-Bat, while he and his fiancee, Francine marry and have a daughter, Rebecca. Langstrom later refines his serum, enabling him to retain his human intelligence while in bat form, and allowing himself control over his transformations.

He first clashes with Batman when he tries to steal the chemicals needed to reverse his transformation, but his control over the new animalistic instincts resulting from his bat like state is tenuous and Batman is forced to subdue him in order to administer the antidote. While it works, it has a horrible side effect: it transforms him gradually into a hideous humanoid bat-like monster.

Kirk Langstrom, a scientist specializing in the study of bats, develops an extract intended to give humans the bat's sonar sense and tests the formula on himself because he was becoming deaf.
