When Merlin is weighed down by sorrows, Jack and Annie travel back to feudal Japan to learn one of the four secrets of happiness.

Jack and Annie travel in their magic tree house to the land of the mystical selkies to seek a magical sword for Merlin.

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

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 back in time to Egypt and meet Florence Nightingale, who is on the trip that will influence her life and the decisions that will make her famous.

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.

Jack and Annie must travel back in time to New Orleans in 1915 to help a teenaged Louis Armstrong fulfill his destiny and become the "King of Jazz."

Jack and Annie travel back to Victorian London when Merlin asks them to use their magic to inspire Charles Dickens to write "A Christmas Carol."

Jack and Annie experience a series of time-travel adventures. (Dolphins at daybreak) It's sink or swim for Jack and Annie when the magic tree house whisks them off to the middle of the ocean. (Ghost town at sundown) "Is this town haunted?" Jack and Annie wonder when the magic tree house takes them to the Wild Wild West. (Lions at lunchtime) "Where are the lions?" Jack wonders when the magic tree house whisks him and his sister to the vast plains of...

As a thank-you from Merlin and Morgan, Jack and Annie are sent on what should be a vacation at a luxurious resort in Cozumel, Mexico, but is, by mistake, an adventure with ancient Mayans, instead.