Leaving only a cryptic note, Andrew and Evie's mother vanishes on their eleventh birthday. Now, almost a year later, the twins receive a mysterious package from someone named Spy X. They soon learn that the contents of the box will lead them on an incredible journey toward finding their mother - and into a world where no one's identity can be trusted. In Book #1, Andrew and Evie aren't initially sure what to make of the package that arrives at their...

Nancy arrives in Phoenix, Arizona, eagerly looking forward to a fun-filled vacation at Shadow Ranch, but abruptly finds herself involved in a baffling mystery. The ranch is being haunted by a phantom horse and maliciously damaged by an unknown enemy.

When a puppy who is being trained as a police dog goes missing, third-grader Judy forms a detective agency to solve the mystery, imitating her literary heroine, Nancy Drew.

Nancy and her friends, in search of information about a UFO, become involved in another mystery involving the inheritance of an old man who lives in the forest.

The Alden children draw upon their resourcefulness to save the neighborhood firehouse from being torn down, while they also face a series of mysterious incidents connected with it.

Marvin looks for clues after suspecting that his new neighbor is a werewolf and involved in a murder conspiracy.

When Dink, Josh, and Ruth Rose visit Washington, D.C., just before Christmas, they are inadvertently caught up in a kidnapping plot that was intended for the president's dog, but also involves the president's stepdaughter and her friend Marshall.

School protectors Ben, Jill, and Robert leap at a final chance to save their school from being torn down to make room for a seaside amusement park, a demolition that is supported by dastardly janitors Lyman and Wally.

Tyler and Lymie, eighth grade misfits, discover a dead body in a quarry and work to uncover the mystery behind it.