When his father remarries and moves his new wife and daughter into the soon-to-be completed Mangrove Hollow, eleven-year-old Nicholas Vargas finds an ally in his new stepsister when a little nixie with a huge problem comes to him for help.

Identical twin sisters Andie and Caitlin decide to switch identities after a fitness test threatens to ruin Caitlin's entire school year.

Dan Cahill and his sister Amy travel from the hottest to the coldest regions of the world in order to stop someone from using their own power against them.

Sarah, her brother Billy, and her parents are moving into her deceased grandmother's house for the summer in order to fix it up and sell it, but this is a house of locked rooms and many dark and dangerous secrets.

When eighth-grader Cameron Boxer creates the Positive Action Group at school he intends it as a diversion to fool his parents, teachers, and sister into letting him continue to concentrate on his video-gaming--but before he knows it other kids are taking it seriously, and soon the boy who never cared about anything becomes the center of everything, whether he likes it or not.

An escalating race to find the 39 Clues finds Amy and Dan pursuing a Clue guarded by thousands of the world's best-trained soldiers, an effort that separates them in explosively dangerous ways.

When sisters Even and Odd are trapped and unable to return home to the mundane world they live in, they, with the help of a unicorn named Jeremy, must stop a power-mad wizard from creating an ecological disaster.

Fairy-tale detectives Sabrina and Daphne Grimm face their first case without Granny Relda's help when the future gets mixed up with the past in Ferryport Landing, and because some of the future does not look bright, Puck helps them try to make some changes.

Awakening stranded on a tropical island with no memory of what happened, Aster investigates a secret underwater world to find her missing sister, while Sam connects their disappearance to suspicious events in his own life.