10-year-old Lucy tries to make the world a little better every day - together with her best friend Rima and her family, who sell ice cream according to an old family recipe. But then the ice cream machine breaks down and the business is threatened with closure because the bank won't grant a loan. That's when she gets the idea to rob a bank. Class gangster Tristan gives her lessons in the disciplines of stealing, lying, fraud and blackmail. But she doesn't turn into a cunning Lucyfer as easily as she thinks.