Austria, 1818: Disaffected orphan Marcus is recruited by his pastor, Father Joseph Mohr, to evict mice from their church organ. But the boy's efforts to preserve the rodent family's home leads to the instrument's destruction. Determined to bring home a replacement choir piece in time for Christmas Eve, Marcus navigates a crippling snowstorm, a saboteur owl, and his own lack of faith in order to earn redemption. With the help of Mozart (his faithful rodent pal), Ed (a moose who dreams he's a reindeer), and Ol' St. Nikolaus himself, Marcus discovers his true faith delivering home the classic carol Silent Night: a belief in himself that was hiding in his heart all along.