While dealing with changes at home, sixth-grader Josh and his friend Aaron use the computer at their New York prep school to travel through time, learning some secrets from the school's past and improving Josh's home situation.
Eight-year-old Jack and his younger sister Annie use the magic tree house to travel back to the Middle Ages, where they explore a castle and are helped by a mysterious knight.
One minute they're looking at pictures of knights in the book, a birthday gift from Joe's magician uncle, the next minute they're battling fire-breathing dragons. Will Joe, Fred, and Sam escape death?.
After Ashley and Kristi find an antique doll buried in old Miss Cooper's garden, they discover that they can enter a ghostly turn-of-the-century world by going through a hole in the hedge.
Artemis's fairy friends help him travel back in time to find a cure for his mother's rare disease which can only be cured by the brain fluid of now-extinct African lemurs, and is shocked to discover that it was actually his younger self who was responsible for bringing about the animal's extinction.
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.
When Jack and Annie travel back to the Kansas prairie in search of "something to learn," they gain an understanding of how hard life was for pioneers and they experience the terror of a tornado.
