As her mother prepares to be a contestant on the 1980s television game show, "The $20,000 Pyramid," a twelve-year-old New York City girl tries to make sense of a series of mysterious notes received from an anonymous source that seems to defy the laws of time and space.

Fifteen-year-old Kate finds herself transported back in time to 1850 in her Connecticut town where she must adjust to the prejudices against Irish immigrants.

Sixteen-year-old Alaric discovers how to travel to an alternate reality, where his mother is alive and his place in the family is held by a girl named Naia.

Fourteen-year-old Bobby Pendragon, apprentice to his Uncle Press, a Traveler responsible for solving interdimensional conflict, tries to locate the legendary lost land of Faar which may hold the key to the survival of the water-covered territory of Cloral, which stands on the brink of war.

Seventh-grader Arthur Penhaligon returns to the parallel universe known as the House to fight his latest enemy, Grim Tuesday, whose greed threatens to destroy both the House and the Earth.

As thirteen-year-old Rory continues his mission in Mannahatta, a spirit realm that co-exists alongside modern-day New York City, filled with fantastical creatures and people from the city's colorful past, he discovers that his father, whom he never wants to see again, is the only hope for peace.

In the mid-1950s, Yggdrasil Birnbaum and her friends, Seamus and Neddie, journey to Old New Hackensack, which is on another plane, to try to learn why ghosts are disappearing from the Birnbaum's hotel and other Hollywood, California, locations.

Having used their magic tree house to travel to India, where they must get a gift to help free the dog Teddy from a spell, Jack and Annie have adventures involving a tiger and other endangered jungle animals.

Jonah, Katherine, Chip, and Alex suddenly find themselves in 1483 at the Tower of London, where they discover that Chip and Alex are Prince Edward V and Richard of Shrewsbury, imprisoned by their uncle, King Richard III, but trying to repair history without knowing what is supposed to happen proves challenging. Author's note includes historical facts about the princes and king.

The fifteen-year-old Murry twins, Sandy and Dennys, are accidentally sent back to a strange Biblical time period, in which mythical beasts roam the desert and a man named Noah is building a boat in preparation for a great flood.