In his quest to fulfill a promise made to his wife, Calvin sets out to right his wrongs and make it the best Christmas ever. If only it weren't June, and the majority of the population, including his wife and daughter, hadn't returned from the dead as flesh-eating snappers in search of hot human lunches, he'd be in pretty good shape. Driven by guilt in a race against the apocalyptic clock, Calvin teams up with G.M., a wily ex-garbage man turned undead slayer, as together they attempt to deck the halls during the most magical time of the year. It's Christmas in June. And snappers be damned... The lights and decorations are going up.