Ellie Anders and Lex are on the case! Today is the long-awaited release of the new video game Surfing Snakes. As Ellie and Lex wait in line to buy it, the store owner, Mrs. Lopez, bursts out and announces that someone has stolen all of them! Ellie and Lex set out to catch the thief. They track down clues, confront suspects, and get help from unexpected friends. Is the thief a trusted store employee? An older boy who makes fun of Ellie? Or whoever left the muddy footprints?