This Christmas, Ruby's family is visiting Granny and Pop, whose house full of breakable items is not the place for a very naughty reindeer. So Ruby is sent to the zoo for the holidays, and she has to bunk in with the stuck-up antelopes and the fussy zebras, which is no fun at all for an excitable reindeer. So on Christmas Eve, Ruby opens all the enclosures, hoping for fabulous festivities and feasting—and creates chaos! With all the animals on the loose, and Santa delayed from delivering all his presents—how can Ruby right her wrongs and save Christmas for everyone?