Margaret Peterson Haddix

When thirteen-year-olds Jonah and Chip, who are both adopted, learn they were discovered on a plane that appeared out of nowhere, full of babies with no adults on board, they realize that they have uncovered a mystery involving time travel and two opposing forces, each trying to repair the fabric of time.

Throughout the hunt for the 39 Clues, Amy and Dan Cahill have uncovered history's greatest mysteries and their family's deadliest secrets. But are they ready to face the truth about the Cahills and the key to their unmatched power? After a whirlwind race that's taken them across five continents, Amy and Dan face the most the difficult challenge yet -- a task no Cahill dared to imagine. When faced with a choice that could change the future of the world,...

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.

When thirteen-year-old Luke Garner unwittingly sets off a rebellion which sweeps the country and ousts the Population Police from power, he quickly realizes that the new regime is corrupt and he may hold the only key to true freedom.

Time travelers Jonah and Katherine arrive in 1611 to rescue missing child John Hudson, son of the explorer Henry Hudson, but just as the mutiny on the Discovery is supposed to start, Jonah and Katherine's knowledge of history is tested once again, and they fear that more is at stake than just one boy's life. Author's note includes facts about Henry Hudson's explorations.

When a diphtheria epidemic hits her 1840 village, thirteen-year-old Jessie discovers it is actually a 1995 tourist site under unseen observation by heartless scientists, and it's up to Jessie to escape the village and save the lives of the dying children.

Jonah was able to save all of time from collapsing but in doing so gained a twin brother, Jordan, who must learn what has happened and do his own part to save time--and his parents.

Fourteen-year-old Avery Armisted and sixteen-year-old Kayla Butts, once good friends, begrudgingly travel to Spain together for a summer vacation where they uncover a secret their families kept hidden from them their entire lives.

Janie's parents move to the suburbs so she can go to a better school, but when she discovers that all the other students are richer than she is, she feels out of place--until she realizes that there are more important things than money.

While playing in the championship softball game, star pitcher KT Sutton blacks out and awakes to a changed world where the roles of academics and sports at her middle school have flipped, making talented athletes, such as KT, outcasts and brainy nerds popular.