These days Terry Deary is best known for his "Horrible Histories" series, though back in the nineties my sister and I loved his "True Stories" books, whether they be Spy, Horror, Monster, Mystery, War or Ghost (and there were plenty more than that).
There were about seven non-fiction stories in all, each with a "fact file" at the end which elaborated on some of the plot-points and gave other examples of the subject material.
"True Spy Stories" runs the gamut from Ancient Greece to World War II, and Deary's confidential prose brings young readers into the world of spy-craft and espionage. He covers Alexander the Great's investigation into his own assassination attempt, the Culper Ring and its dealings under the direction of George Washington, the movements of the Secret Police during the Russian Revolution, the French Underground during WWII, the discovery of a German spy in Scotland in 1940, and the dawn of internet hacking in the 1980s.
Along the way he drops plenty of names of famous historical figures that were embroiled in spying, from Mithradates to Francis Walsingham to Agent 355. There is just enough to hook a young reader's interest, hopefully leading them to seek out further information. He also covers things such as codes, secret messages, and other essential elements of espionage.
David Wyatt also provides evocative illustrations throughout, and an introduction and epilogue written by Deary to hook readers on the subject. Quick, easy and engrossing reads, which might be especially rewarding for reluctant readers.