Eleven-year-old Max Martin and his fellow scooter riders Oscar Santiago and Lily Blue (and her pet chameleon, Speck) are hot on the trail of a thief in a puzzling case: Max saw a strange green bicycle whiz by him onto a bridge. But it never came out the other end! How could it have vanished? The thief on the bicycle stole two very important things, and now it's up to Max, Oscar, and Lily to use their clues, and their scooters, to find them. It will take the best scooter skills they have, and a wild scooter ride, for the three friends to catch the crook!