The elves can't be kept on shelves in this hilarious middle-grade debut about what happens when Santa opens a contest to find his successor.These elves are off the shelves.Ollie and Celia think they know what the life of an elf is supposed to be like: Make toys. Help Santa. Make more toys. Help Santa. Try out a new ice-cream flavor. Help Santa.But then Santa rocks the North Pole with a surprise announcement He's decided this is going to be...