When Jonah and Katherine travel to early 1900s Switzerland and Serbia to return Albert Einstein's daughter, Lieserl, to history, her mother Mileva grasps entirely too much about time travel and has no intention of letting her daughter go.

Four cousins, Roger, Ann, Eliza, and Jack, have an extraordinary summer when, after an old toy soldier comes to life, they find themselves transported back to the days of Robin Hood and Ivanhoe.

Thirteen-year-old Atticus "Tick" Higginbottom begins receiving mysterious letters from around the world signed only "M.G.," and the clues contained therein lead him on a journey to the perilous 13th Reality and a confrontation with evil Mistress Jane.

Arthur must retrieve the Second Key from his enemy Grim Tuesday in order to save the world. Arthur doesn't think he will ever have to return to the strange house that nearly killed him on Monday -- the house that contains an entire world. But Tuesday brings new challenges -- in the form of an enemy named Grim Tuesday, who threatens the well-being of both Arthur's family and his world. Arthur must retrieve the Second Key from Grim Tuesday in order...

Science-loving Delia Bean is expecting to have a pretty boring summer vacation, but when her Uncle Lyndon offers her an internship in his Earth Time Museum, everything begins to look better.

"Lucy Usthorn of Fort Worth, Texas, is super excited for her class trip to the Natural History Museum. Sure, Ms. Brock, the strict school librarian who happens to be dating Lucy's dad (awkward) is chaperoning. But it'll still be the best day, right? Wrong! Lucy watches in shock and humiliation as her dad proposes to Ms. Brock. Lucy is distraught. If only she could do this day over from scratch... Enter the magic bracelet. It arrives in the mail, with...

Finn and his friends travel to the Subatomic, a microscopic world where Finn hopes to find his father and defeat the Plague once and for all.

As time plays tricks and night falls without warning, Johnny, Dizzy, and Charlie, who are lost in the woods, must elude the danger that lurks in shadows and work together to find a way out. Includes note about the science behind the story. Secrets, spies or maybe even a monster... What lies in the heart of the wood? Charlie, Dizzy and Johnny are determined to discover the truth, but when night falls without warning they find themselves trapped in...

As her mother prepares to be a contestant on the 1970s 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.

"In two parallel universes, eighteen-year-old Chris navigates the summer before college--in one universe he is forced to spend three months with his emotionally distant father in California, and in the other he remains home and deals with a swiftly changing friendship" --