In a society that allows families to have only two children, a group of third-borns tries to save itself and others like them.

A twelve-year-old girl raised in a foster village is returned to her biological parents, and discovers home is not what she expected it to be.

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.

In a future where the law limits a family to only two children, third-born Luke has been in hiding for the entire twelve years of his life, until he enters boarding school under an assumed name and is forced to face his fears.

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.

Many surprises await twelve-year-old Edwy Watanaboneset when the Freds return him to Cursed Town, including that he has siblings in Refuge City who he will join in boarding school.

After returning the missing children from history to their original time periods, thirteen-year-old Jonah must save time itself when aviator Charles Lindbergh mysteriously appears and kidnaps Jonah's sister.

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.

Follows fifth grader Max as he searches for his best friend who disappeared, leaving behind a strange note.

Twelve-year-old twins Nick and Eryn and their robot stepsiblings, Jackson and Ava, try to save humanity from killer robots.