Marco Polo, brave explorer

"Marco Polo is a retired Christmas ornament, but in his mind he is a great mouse explorer. Because he's tiny and likely to be lost, he is the least-borrowed of the Book Buddies--toys that children can check out of the library just like a book--and he almost never leaves the library. But the little mouse finally meets the right match in Seth, a boy who is about to attend his first sleepover. If Seth were to bring the stuffed bunny he usually sleep...