10-year-old Lucy is basically too good for this world. She is well-behaved, kind and perfect in every situation. Her best friend Rima and she herself want to make the world a little better with every little action. But then disaster threatens: Lucy’s parents run an ice cream parlor, and when the expensive ice cream machine breaks down, the parlor is threatened with closure. Lucy wants to prevent this at all costs. However, after much deliberation, she sees only one way to get money quickly: a bank robbery. To prepare for her big coup, she makes a deal with the class gangster Tristan. Under the code name “Operation Lucyfer”, he is supposed to teach her how to be mean and ruthless. So Lucy gets tutored in stealing, lying, cheating and blackmailing – and proves to be an amazingly docile student. Lucy barely recognizes herself. Her transformation from nerd to crook, however, causes many problems.