At the flea market nine-and-a-half-year-old Chase and his younger sister Ava acquire an old suitcase filled with rows of carefully packed strange objects, and when they handle one of the objects (a dragon-headed doorknob) they find themselves in King Arthur's castle, on a mission to save the King--and pursued by a strange man whom they first saw at the flea market, who is after their suitcase.

Guided by a magic rhyme, Jack and Annie travel to ancient Baghdad on a mission to help the Caliph disseminate wisdom to the world.

"The future has been saved, but at a cost: Fort Fitzgerald has been expelled from the Oppenheimer School, and some of Fort's friends have been lost in time. But time is the one thing Fort, Rachel, and Jia don't have, as they'll soon be facing one of the eternal Old Ones, the Timeless One, for the fate of the world. If they lose, the Old Ones will return, and humanity is doomed. If they win, the Old Ones will still return, and humanity is doomed. Because...

Dak, Sera, and Riq find themselves stranded thousands of years in the past and their only hope is the Mayas who know a great deal about the future.

When Nancy, Bess, and George continue their journey and board a train bound for Denali National Park, they become aware that danger has followed them and Nancy worries her undercover status has been discovered.

When the mysterious first aid kit takes golden retriever Ranger to New Orleans shortly before Hurricane Katrina hits, he finds himself helping Clare Porter and her grandmother, who are waiting for Clare's father at their home in the Lower Ninth Ward--and when the levees break and Clare is separated from Nana, Ranger must somehow get her to the relative safety of the Superdome, and reunite her with her family.

When Finn is saved from the Time Rangers by an older version of himself, it comes with a catch. Old Man Finn needs Finn and his friends, Lincoln and Julep, to help him win battles he lost years ago against the Paradox, a terrible creatures obsessed with revenge against Finn's father. If they succeed, he promises to tell Finn where his father is. He even gives them a pair of time-traveling pajamas to help them with their quest. There's only one problem....

The mysterious box that Ranger the golden retriever found in the garden transports him back to first century Rome, where he must rescue Marcus, a young servant boy, and Quintus, a volunteer gladiator, from the brutal world of the Colosseum.

Eric and his friends travel through time into Droon's dark and dangerous past in order to save not only Droon but also the Upperworld.

Dinosaur Club member Jamie meets a fellow club member while exploring his new home of Ammonite Bay, and together they discover some dinosaur footprints that transport them back to the prehistoric era where they must call on the Dinosaur Club for help.