WorldLeo is 17 and Max's big brother. Leo lives in a "limited universe," as Max calls it, so Max has to keep an eye on him. Leo and Max are at home alone when a raven bangs against the windowpane and lies on the ground half dead. He's ringed, so Max can find out where he's from. Leo is convinced that the ring is a wedding ring and Mr. Crow has to go back to his wife to get better. Whenever Leo is convinced of something, nothing and nobody can stop him. He sets off to bring Mr. Crow back to the Raven Research Station, and Max has to come with him whether he likes it or not. It takes a whole day to get there. On their trail they leave: a fake car mechanic, a totalled lawnmower tractor, two Vikings, a cow with a handcart, an ice cream truck, a broken raft, God, once nearly drowning, a quad and a helpful student.