"I didn't do it! I don't know anything about his tire!" Mark Prescott's in trouble. Not only did he fight with Joe Devlin, but now Joe accuses Mark of slashing the tire on his new bike. He didn't do it, but how can he prove his innocence? By finding the culprit! But playing detective isn't as easy as it is on TV. As Patti, Mark's best friend, plays Dr. Watson to his Sherlock Holmes, Mark encounters a crows of potential villains. There's Rachel, a girl Joe teased about being fat. And Chad, the boy who had an argument with Joe. Even Patti is under suspicion. With the help of his wise friend Whit, the eccentric inventor, Mark untangles the mystery and learns new lessons about friendship and family ties.