Trapped in a vat of chemicals in the Ace Chemical Processing Plant, Batman calls out to Harley Quinn to let him out, or else the Joker will be able to make his next move. Crestfallen, Harley responds that, maybe, he will be turned into what the Joker turned into; be like he was before he changed. She is gone, and as the chemicals swim up around him, Batman recalls how he had examined the composition of the soup that birthed the Joker, and no matter how many times, he could never see what might have caused that man to survive it. There's nothing in the mixture but death.