Jingle (Swindle #8) by Gordon Korman; 2016. Hardcover (Ch-FIC)

JINGLE: a light clinking or tingling sounds, often heralding the approach of Santa, reindeer, or the mysterious thief of a priceless possession . . . Griffin Bing and his friends are NOT happy. Instead of going away for winter break, they've been signed up to volunteer at a local Christmas extravaganza . . . as elves.It's not easy being an elf. Not when Santa is bad news and Rudolph is being played by a Doberman who makes up his own rules wherever he goes.But being an elf is nothing compared to being blamed when a prized Christmas possession -- worth over ten million dollars -- is stolen right from under your nose.It's time for these elves to get off the shelf and track down a Christmas thief!