GERONIMO STILTON Book 6: PAWS OFF, CHEDDARFACE!
What in the world is going on? Geronimo is repeatedly accused of actions he has no memory of taking. He discovers his face and name on a toilet advertisement. He hears that he's been popping wheelies on a motorcycle, insulting his friends, and more. But he remembers none of it.
Geronimo finally discovers someone is immousenating him! The imposter takes over Geronimo's job, his home, and his friends. He must get to the bottom of the dastardly plot --- especially after the phony Geronimo sells Geronimo's newspaper to the dreadful competition.