Hour of the Olympics: Their magic tree house takes Jack and Annie back to retrieve a lost story in ancient Greece, where they witness the original Olympic games and are surprised to find what girls of the time were not allowed to do. Viking ships at sunrise: Their magic tree house takes Jack and Annie back to a monastery in medieval Ireland, where they try to retrieve a lost book while being menaced by Viking raiders. Day of the Dragon-King: The magic treehouse takes Jack and Annie back two thousand years to ancient China where they must find the original copy of an old legend before the Imperial Library is burned down by the evil Dragon King. Vacation under the volcano: Their magic tree house takes Annie and Jack to Pompeii just as Vesuvius is about to erupt, and they must find a Roman scroll before everything is covered with burning ash. Polar bears past bedtime: Their magic tree house takes Jack and Annie to the Arctic, where a polar bear leads them onto very thin ice. Lions at lunchtime: The magic tree house takes Jack and Annie to Africa where they meet up with wonderful wild animals, a very hungry warrior, and where they even solve a riddle. Ghost town at sundown: Their magic tree house takes Jack and Annie back to the Wild West, where they experience excitement and danger and try to solve a riddle. Dolphins at daybreak: Their magic tree house takes Jack and Annie deep into the sea, where they meet up with dolphins, sharks, and octopi as they search for the answer to an ancient riddle.