Ethan Cheeseman and his children, ages eight, twelve, and fourteen, hope to settle in a nice small town, at least long enough to complete work on a time machine, but spies and government agents have been pursuing them for two years and are about to catch up.

As the youngest operative in a secret agency, the reader is asked to make choices throughout the story to save the world from an invasion of monstrous bugs.

Rookie, an agent with the Elite Penguin Force, invites young readers on a mission to help him to protect Club Penguin from harm.

Ten-year-old Andrew North believes his father and brother are spies, and spends his time in middle school preparing to join the family business.

Ten-year-old Matt and six other children travel to 1776 Boston, living out American history as they meet Benjamin Franklin, learn about colonial medicine, and become part of a rebel spy ring.

My sister, Thea, is the mystery-loving rodent, not me! But somehow I found myself going undercover to get to the bottom of a case. Slimy Swiss balls -- I hardly knew where to start! Geronimo Stilton, Secret Agent Mouse? Maybe I could get used to that. . . .

Eleven-year-old Harriet keeps notes on her classmates and neighbors in a secret notebook, but when some of the students read the notebook, they seek revenge.

Sophie already proved her supersleuth skills when her piggy bank went missing - she tracked it down in no time. But being a successful snoop is harder than it looks.

Michael K. just started fifth grade at a new school. As if that wasn't hard enough, the kids he seems to have made friends with apparently aren't kids at all. They are aliens who have invaded our planet disguised as school children and a hamster. They have a mission to complete: to convince 3,400,001 kids to BE SPHDZ in order to save the world!

Twelve-year-old Ben Ripley leaves his public middle school to attend the CIA's highly secretive Espionage Academy, which everyone is told is an elite science school.

Alex, Alice and Alistair think they are just three ordinary mice, until Alistair mysteriously vanishes. Then Alex and Alice learn a secret about their family: a secret which means Alistair's life is in danger - unless Alex and Alice can find him first.

When the children uncover a strange puzzle in a friend's back yard, it's the start of a "spy game" leading to gold. But first they must make sense of an old photo and a riddle, and learn just who is behind this mystery within a mystery.