"When the Claymore Diamond is stolen from Ravensburg's finest jewelry store, Stanley Carusoe gets the bright idea that he and his friends should start a detective agency. Armed with curiosity and their love for math, Stanley, Charlotte, Gertie and Felix race around town in an attempt to solve the mystery. Along the way, they butt heads with an ambitious police chief, uncover dark secrets, and drink lots of milkshakes at Mabel's Diner. But when their backs are against the wall, Stanley and his friends rely on the one thing they know best: numbers. Because numbers, they never lie."--Back cover.