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.
Lulu's Mysterious Mission
by Judith Viorst
Lulu has put her tantrum-throwing days behind her. That is, until her parents announce that they are going on vacation--without Lulu. Not only that, but they are leaving her with the formidable Ms. Sonia Sofia Solinsky, who reveals an astonishing secret.
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.
Starring Jules (Super-Secret Spy Girl)
by Beth Ain
Second grade is over and Jules is on her way to Quebec to film a spy movie, but she misses all her friends, and with only a hockey player and a diva starlet as cast mates in a place where nobody speaks English, she is feeling lonely--and her mother will not even let her go bungee-jumping.
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.