The film is adapted from the book series written by Eoin Colfer, which takes place partially in the real world and partially in a fantasy world underground where every Irish legend about fairies, pixies, trolls and dwarfs is true. When the titular character's father goes missing, he is tasked with saving his life by finding and recovering an ancient artifact. That's when Artemis' world becomes 100 percent more magical (and 100 percent more dangerous).