Growler's Horn — Mark Delaney

Meet Misfits, Inc. Investigations: Peter, the genius; Jake, the athlete; Byte, the computer whiz; Mattie, the “magician.”
These four teenage super-sleuths have a knack for uncovering and solving unsolvable crimes. In this third installment, the team attends an auction so that Jake, an aspiring musician, can buy a clarinet. Once he's acquired the clarinet, the Misfits find an odd, handwritten note hidden inside the instrument.
Soon they discover that the clarinet once belonged to a promising jazz musician named Growler Morton, who mysteriously disappeared in the 1950's, as did three million dollars of his record company's money. When the clarinet is stolen the Misfits find themselves driven to unravel the secret of Growler's horn, attempting to restore the good name of an innocent man.
Featuring an engaging group of outcasts with varied interests, each book in the Misfits series offers an intriguing mystery, supported by Delaney's well-paced plot and believable dialogue, that will keep readers captivated to the very end.