The Queen of Hearts is a crazed serial killer who believes she has an abnormal heart condition which she believes causes her to take the hearts of other's in hopes of one day receiving a transplant. Batman first came across the Queen of Hearts in Gotham. They had been fighting on a rooftop and she fell over the side. Batman caught her and pulled her up even though she had begged him to let her fall and die. The Queen of Hearts knew she couldn't control her urges and that she would kill again. She knew she would kill again whether she tried to go straight or she was locked away. Batman saved her anyway.
Three years later, Batman caught wind of a series of murders in Rio de Janeiro matching the Queen of Hearts's modus operandi - the victims being attacked with a drill, their ribcage opened, and their hearts removed. Batman traveled to Rio to investigate and see if it was truly the Queen of Hearts who was responsible for the killings. Batman found her and the two fought but they also came across a psychic being known as The Idiot who sucked her mind dry, leaving the Queen in a catatonic zombie-like state.