Magic Tree House #13
Vacation Under the Volcano
This book sees Morgan le Fey sending Jack and Annie to Pompeii before Mount Vesuvius erupts to save a lost scroll. The magic tree house transports them to Pompeii and makes sure they fit in by dressing Jack and Annie with clothing that is appropriate for the place and time they are in.
Jack and Annie meet a soothsayer who says the end is near. They realize that they are in Pompeii the day that Mount Vesuvius erupts.
In a race against time Jack and Annie are searching for a lost scroll. Do they are don't they get back in time? Read the book and find out!