When eight-year-old Jack and his seven-year-old sister, Annie, join a group of nineteenth-century explorers aboard the H.M.S. Challenger, they learn about the ocean, solve the mystery of its fabled sea monster, and gain compassion for their fellow creatures.

Jack and Annie travel 500 years back in time to Florence, Italy, and spend a day helping Leonardo da Vinci in the hope of learning another secret of happiness.

"The magic tree house has taken Jack and Annie back in time to England in 1944. England is fighting for its life in World War II. Before long, Jack and Annie find themselves parachuting into Normandy, France, behind enemy lines. The date is June 5. Will the brave brother and sister team be able to make a difference during one of the darkest times in history?"--Provided by publisher.

Jack and Annie travel back to nineteenth-century Ireland to inspire a young Augusta Gregory to share her love of Irish legends and folktales with the world.

"Jack and Annie travel in the magic tree house to Galveston, Texas on September 8, 1900--the day of the worst natural disaster in US history"--

"Travel to Ancient Greece with Jack and Annie as they meet Alexander the Great and help tame his wild stallion"--Provided by publisher.

Jack and Annie travel to Vienna, Austria, in 1762 where they meet the young Wolfgang Amadeus Mozart and his sister and help save the budding genius' life.

Eight-year-old Jack and his younger sister Annie find a magic treehouse, which whisks them back to an ancient time zone where they see live dinosaurs.

The magic tree house whisks Jack and Annie to India during the Mogul Empire in the 1600s to search for an emerald needed to break a magic spell.

The magic treehouse takes Jack and Annie to a moon base in the future, where they continue to search for the fourth thing they need to free their friend Morgan from the magician's spell.