Geronimo Stilton, Secret Agent
by Geronimo Stilton
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. . . .
Harriet the Spy
by Louise Fitzhugh
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.
Playing With Fire
by Bruce Hale
Reluctant orphan-turned-spy Max Segredo discovers intrigue at the Merry Sunshine Orphanage and must confront an international group bent on world domination, while uncovering mysteries from his past.
Sophie the Snoop
by Lara Bergen
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.
SPHDZ. Book 1, Spaceheadz
by Jon Scieszka
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!
by Stuart Gibbs
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.
The Spy Game
by Gertrude Chandler Warner
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.