When a young boy and his mother move house, the boy discovers a secret box hidden under the floorboards of his bedroom. In the box, he finds a hat, scarf, some lumps of coal and a shriveled tangerine - it's a snowman-making kit! Later that day it starts to snow and the boy builds a Snowman and with the little spare snow leftover, a Snowdog. That night they come to life and take him on a wonderful adventure. As dawn breaks they fly home, but before the boy returns to bed a magical surprise awaits him...