"Run!" cried Grace. "It's a ... snow tornado!"

It's the height of summer in Moreland, and Grace Griffin and her fellow warden Tom Eely are sweltering in the heat until they answer a strange call for help that comes through on the amazing Griffin map.

After teleporting to Oakwell, they find the town paralysed by a freezing snowstorm, which is ruining the famous summer market that brings in visitors and trade.

Using their mystery-solving skills and amazing inventions, can Grace and Tom find the cause of the weird weather and restore summer from the snow?