The year is 1955. Summer has come upon the sleepy little town of Turlock, California, and good friends Jupiter Jones, Howie Jones, and Bobby Andrews plan to spend their summer days like they always do; hanging out in the treehouse, cruising Sierra Street, and of course, solving a mystery or two. The three boys compose the detective agency known as the Stray Cats, and haven’t spent a summer without solving a case. But this summer, everything will change. A new boy named Peter Crenshaw moves onto Sierra Street and the boys invite him into their club. But when Peter faces a deadly encounter during initiation, and Howie goes missing during a string of robberies, the boys must find the courage within themselves to solve the mystery of Sierra and become heroes.