Jack and Annie go on a series of missions in order to help the wizard Merlin, traveling to such places as Japan, Antarctica, New Orleans, and Ireland.

Dogs in the dead of night: Jack and Annie travel to a monastery in the Swiss Alps where, with the help of St. Bernard dogs and magic, they seek the second of four special objects necessary to break the spell on the wizard Merlin's beloved penguin, Penny. Abe Lincoln at last!: The magic tree house whisks Jack and Annie to Washington D.C. in the 1860s where they meet Abraham Lincoln and collect a feather that will help break a magic spell.