Book excerpt: When Sam visits Zara and Ben and their great-uncle, the quirky inventor Professor Ampersand, he never expects to embark on a fantastical adventure. But when Professor Ampersand and his group of professor friends are kidnapped by the evil Professor Murdo, it's up to Sam, Zara, and Ben to save them. They have only three days in which to journey to an icy, desolate land and uncover Murdo's sinister plot. Only then can they save the professors— and the fate of the whole world.