Batman: The Killing Joke (1998)

The man who later on becomes the Joker is an unnamed engineer who resigns from his job at a chemical company to become a comedian, but ends up failing either way. Since he has to do something to support his pregnant wife, he accepts the offer to guide two criminals through a chemical plant where he used to work in order for them to rob the playing card company next to it. During their planning, the police calls to inform him that both his wife and unborn child died from a household accident.