Marco Polo is a mouse Christmas ornament that the librarian thought was too cute to be put away. Marco Polo pretends he's a brave adventurer because he often finds himself in tight spaces, like behind the refrigerator. But really, he's afraid of being lost. He's borrowed by Seth, who has been invited to his first sleepover at a friend's house. Seth is excited, but also afraid of spending the whole night away from home. They face their fears together when Marco Polo comes on the sleepover and gets lost.
