Dr. Peter Corso was a famed surgeon and prosthetics expert for people who lost limbs.
During his first twenty years of practice, Dr. Corso dedicated all his time to helping others, one of whom happened to be his friend, Bruce Wayne, who bought some servomotors from Corso for his new batsuit. One day, however, he met April, his new nurse. Corso gradually fell in love with her and a couple of weeks later he proposed, which she vigorously accepted.
Not long afterward, Corso met Harold and did a wrist replacement on him. However, Harold wanted more and insinuated a profitable partnership. Corso, on the other hand, declined the obscure innuendo, claiming he already had everything he wanted. A week later Corso returned home to find that Harold's gang had broken in and kidnapped April. Corso was blackmailed into mechanically enhancing and upgrading their bodies during the subsequent six months.
Despite the coerced collaboration, Corso secretly rigged the gang's prosthetics with a voice-activated fail-safe which he intended to activate once he recovered his beloved. The robotic enhancements were programmed to auto-destruct with the code phrase "April Moon", which held special meaning for him, being the couple's love song.
During their first crime spree night, the Gang was intercepted by Batman. In the spar, Kneejerk lost a servomotor, which Bruce Wayne recognized as one of Corso's contraptions. Later that night, Corso was confronted by Batman. The doctor seized a moment of oversight to sedate Batman. Forced to lay low, he took a leave of absence and moved his workshop to another facility.
However, when he got news of a tragic accident, he rushed to West End Inn to assist the victim. Much to his surprise, the phone call was but a ruse by Batman to draw the good doctor out. When he realized he had been duped, Corso burst into tears, claiming "they" would certainly kill his wife. He told Batman about the blackmail and fail-safe devices, but wouldn't tell him more in fear of jeopardizing April's life. At that moment, the Gang barged in and Corso played the innocent so as to be on their good side and was allowed to leave.
After the battle that ensued, Corso followed Batman to the gang's lair, suspecting he'd tail them to rescue April. Corso was shocked to find out that not only was April in league with the gang, but she was revealed to be having an affair with their leader, Bullwhip. Heartbroken, Corso howled in despair and accidentally gave away their location but Batman hid him in a cellar for his safety though he later escaped after the fight. After deducing the keyword, Batman defeated the entire Gang, except for Bullwhip, who fled.
Unaware that Corso had seen him with April, Bullwhip sought him for one ultimate enhancement. He told Corso, who realized he had nothing to lose now after seeing his wife betraying him with Bullwhip, not to hold back, to which the doctor nonchalantly agreed that he won't "hold back", by sedating him and bringing a spinning drill disturbingly near Bullwhip's forehead. Bullwhip's fate was unknown though it is hinted that Corso murdered or maimed him.