In the early twentieth century in Swampsea, seventeen-year-old Briony, who can see the spirits that haunt the marshes around their town, feels responsible for her twin sister's horrible injury until a young man enters their lives and exposes secrets that even Briony does not know about.

Twelve-year-old twins Philippa and John have more adventures when they become involved in an international adventure involving the Blue Djinn, the supreme arbiter of all djinn.

"Cassie and Caitlyn Waters may be identical twins, but everything else about them is completely different. The only thing they can agree on is that neither of them is happy that have to move to middle-of nowhere Aura, Texas. Caitlyn tries to put a positive spin on getting a fresh start, but Cassie's busy plotting how to convince their mom they should move back to the big city as quickly as possible. But being the new kids isn't their only challenge....

Through e-mails, letters, blog entries, and movie scripts, twelve-year-old Ruth, an American girl, and Ruby, an English one, discover that they are long-lost twins.

"Gabriel Merrick plays with fire. Literally. Sometimes he can even control it. And sometimes he can't. Gabriel has always had his brothers to rely on, especially his twin, Nick. But when an arsonist starts wreaking havoc on their town, all the signs point to Gabriel. Only he's not doing it. And no one seems to believe him. Except a shy sophomore named Layne, a brainiac who dresses in turtlenecks and jeans and keeps him totally off balance. Layne understands...

As fourteen-year-old telepathic twins struggle to escape the clutches of the Nightrise Corporation, one of them travels through dreams to a time when the evil Old Ones ruled and learns the role that he, his brother, and three other Gatekeepers must play to keep the world safe from the Old Ones' return.

As the Wanteds, Unwanteds, and Necessaries struggle to adjust to changes in their society, Mr. Today begins training fourteen-year-old Alex to replace him as Artime's leader one day while Alex's disgraced twin, Aaron, connives to take over Quill.

Ever since Nor was forced to go to a nearby kingdom in her sister's place, she's wanted nothing more than to return to the place and people she loves. But when her wish comes true, she soon finds herself cast out from both worlds, with a war on the horizon. As an old enemy resurfaces more powerful than ever, Nor will have to keep the kingdom from falling apart with the help of Prince Talin and Nor's twin sister, Zadie. There are forces within the...

Now cured, Fiona Tarsis and her twin, Jonah, set out to find their mother with the help of Bowen and former neighbor Jacqui, planning to spread the cure along the way, but raiders will do anything to stop them and new ally Kevin may have ties to those raiders.

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.