Mat is a young male rat that lives among a rat commune in an abandoned wine cellar, together with his best friend Toby and other rodents. Having felt in love with Nat, a female house mouse kept as a pet in the upper floors, he decides to become a Scavenger, for sneaking to his beloved somehow officially. Being from different worlds, they plot a plan to escape to “the outside” together. His overconfidence however puts them in peril’s way, and not everything in the commune is as it seems.

In a series of unlucky events, Mat finds himself alone, far away from the house. He must make his way back home, overcoming a journey across woodlands, caves, and swamps, defying overwhelming danger of a winged, poisonous, and scale-bond variety. With a rivet for a sword and nails as throwing daggers, Mat will brave a world to which he is unwelcome.