In Snow Pony Express, Grace and Aaron are thrilled when an unexpected snowfall means schools are shut and they can spend all day working at the stables and helping the people of Greenfort get to the shops.

But, while they are out, a blizzard strikes, forcing them to take shelter in a disused barn. When the blizzard finally stops, they discover they're snowed in. Now it's a race against time to rescue themselves and their ponies before night draws in …