One ordinary Monday morning in May, Hilmer Eriksson walks into his high school classroom and discovers that he has become invisible. No one can see him, no one can hear him. In fact, a police detective named Harald Fors arrives at school that very morning to investigate Hilmer's disappearance. The boy has no idea what's going on, but he's frightened, and he's starting to forget things - including what happened to him a few nights earlier. Detective...