(From the publisher):
The Magic Tree House transports Jack and Annie to the freezing Arctic.
There, they must solve the final riddle to become master librarians. But it's
not going to be easy--especially when they have cracking ice, a seal hunter,
and a prodigious polar bear to deal with. Will they be able to solve the riddle
before they get iced themselves?
Original title: Polar Bears Past Bedtime
Genre: Fiction→ Children & Young Adult→ Fantasy
Fiction→ Children & Young Adult→ Adventure