Twins Theo and Alexander and their sister Wil are abruptly dropped off at their Aunt Saffronia's house, where they learn they must complete a series of tasks in order to see their parents again--and their first assignment is at a waterpark.

Arek, having lived his sixteen years in a hole with his small family, sets out into a monster-filled world with his friend Mel to find his fathers and, perhaps, another human.

When Joe goes missing, Brett and Poppy begin to search for him and find themselves transported to a desert city that needs their help to escape destruction by an evil villain.

As young archaeologist Will Burrows continues to search for his lost father in the strange underground world he has discovered beneath the city of London, he stumbles across a sinister plot with terrible implications for the world above.

When a member of their group goes missing, the Thea sisters head to Niagara Falls to find him.

Sarah Merson, an orphan, mysteriously gains admission to isolated and elite Sanctuary Bay Academy, but after her roommate disappears, Sarah discovers a dark truth about the school.

In 1937, teenaged Theodora Fox and her crush, Huck, set out through the Carpathian Mountains seeking her missing father and the cursed ring of Vlad the Impaler, which he was seeking.

In the sleepy town of Shady Oaks, Nancy Drew and her friends investigate an exhibit of photographs, rumored to be cursed, and their connection to the disappearance of two people.

When men start vanishing at sea without a trace, seventeen-year-old Reyna, a Master Explorer, must travel to a country shrouded in secrets to solve the mystery before it is too late.

Mallory Moss knows the rules of middle school. The most important one? You have to fit in to survive. But then Jennifer Chan moves in across the street, and that rule doesn't seem to apply. Jennifer doesn't care about the laws of middle school...Then Jennifer goes missing. Using clues from Jennifer's journals, Mallory goes searching. But the closer she gets, the more Mallory has to confront why Jennifer might have run...and face the truth within herself....