Liar & Spy by Rebecca Stead

When Georges moves into a new apartment block he meets Safer, a twelve-year-old self-appointed spy. Soon Georges has become his spy recruit. His first assignment? To track the mysterious Mr X, who lives in the flat upstairs. But as Safer becomes more demanding, Georges starts to wonder: what is a game and what is a lie? How far is too far to go for your only friend?

Recommended Age: 8+