Born To Spy — Jayde Scott

When thirteen-year-old Thom's father goes missing, Thom knows something's up so he breaks into the basement only to find a spy center full of spy equipment.
With the help of his friend, Danny, and Danny's fifteen-year-old sister, Hilly, the three of them set out to discover what happened to Thom's father, but their investigation brings them to the attention of a powerful group of art thieves who would do anything to protect their identities.

Soon they realize their own life's at stake and Hilly's drama queen antics and focus on spending every penny on the royal spy credit card isn't aiding the mission one bit. Thom will have to rely on his wits and friends if he's to survive and solve the mystery.