April Corso was the wife of Dr. Corso, assumed to have been kidnapped and held to ransom by Bullwhip's gang.
History
Dr. Peter Corso had spent almost his entire life dedicated to his work - that is, until the arrival of his new nurse, April.
April had a seemingly very cheery and optimistic personality, which the doctor took a shine to, eventually causing him to fall in love with her. A couple of weeks passed and Corso proposed, which April accepted. Their marriage was seemingly a happy one, with the song, "April Moon", viewed by the couple as a reminder of their happiness. However, underneath her charm and beauty, April was in fact a cold and scheming opportunist who had in fact married Corso for other motives, demonstrated when a young man named Harold crossed paths with Corso.
Harold attempted to persuade Corso to become involved in a more profitable line of work: that of illegal mechanical upgrades. When Corso refused, he and his gang approached April with an offer to coerce Corso into upgrading their enhanced prosthetics in exchange for jewellery and make it look like a hostage situation. April gladly accepted and began a romantic relationship with Harold.
Six months later, after Harold (now named Bullwhip) and the gang had run in to Batman, Corso followed the crime fighter to where he had discovered the gang's lair, where April's true colours were revealed to both Batman and Corso. Not knowing they were being watched, April took an emerald from Bullwhip as a gift whilst coldly saying how Corso could never afford items of the like and then proceeded to kiss Bullwhip on the lips.
Corso, distraught at seeing his wife had betrayed him in such a way, caused a commotion outside, which the gang heard and investigated. Batman was able to hide the doctor out of sight before they saw him and after defeating the gang, April, Bullwhip and Corso had vanished.
Bullwhip, not knowing Corso had seen him and April together, later visited Corso for one more upgrade (heavily implied to be his "final operation"), but whether April got away is uncertain.