What are some popular adult spy novels?

Sure. 'Alex Rider' series by Anthony Horowitz is very popular. It follows the adventures of a young spy named Alex Rider. Another one is 'The Gallagher Girls' series which features a group of girl spies at a boarding school. Also, 'The 39 Clues' has elements of spy - like adventure for young adults.

In 2021, 'The Coldest Case' by Martin Walker also had elements of spy - like mystery. While it's not a traditional spy novel in every sense, it involves a lot of investigation and secrecy. The story unfolds in a way that makes you feel like you're uncovering a big conspiracy, much like in a spy thriller.

One popular spy novel is 'The Spy Who Came in from the Cold' by John le Carré. It's a classic that offers a gritty and complex look at the world of espionage during the Cold War.

One of the popular 2024 spy novels could be 'The Shadow Agent'. It might involve a complex web of international espionage with a protagonist who has to navigate through dangerous political landscapes and secret organizations.

Well, 'The Princess Diaries' can be considered in a way as it has elements of a girl dealing with a new identity which has some spy - like situations. 'The Girl from Everywhere' also has a strong female lead with a lot of mystery and adventure, much like what you'd expect from spy girl novels. There are also some lesser - known ones like 'Chasing Vermeer' which involves a girl in a mystery that has some spy - ish elements.

Some navy spy novels worth mentioning are 'Ice Station Zebra' by Alistair MacLean. It combines the harsh environment of the Arctic with naval and spy elements. In this story, a British submarine is sent on a dangerous mission. 'The Ship' by C. S. Forester is another. It follows the adventures of a ship's crew during wartime, and there are elements of spying and intelligence - gathering throughout the narrative.

The 'Mitch Rapp' series by Vince Flynn can be considered current in terms of its influence on the spy novel genre. These novels are full of action and political intrigue as Rapp takes on various threats to national security.

One popular spy fiction novel is 'The Bourne Identity' by Robert Ludlum. It follows the story of a man with amnesia who discovers he has a set of highly dangerous skills. Another is 'Tinker Tailor Soldier Spy' by John le Carré. It's a complex tale of Cold War espionage. And then there's 'Casino Royale' by Ian Fleming, which introduced the iconic James Bond character.

One popular MI6 spy novel is 'Casino Royale' by Ian Fleming. It introduced the iconic character James Bond, an MI6 agent. Another is 'The Spy Who Came in from the Cold' by John le Carré, which offers a gritty and complex view of the spy world.

One popular teenage spy novel is 'Alex Rider' series by Anthony Horowitz. It follows the adventures of a teenage spy, Alex Rider, who gets involved in dangerous missions. Another is 'Gallagher Girls' series by Ally Carter, which is about a school for girl spies. Also, 'The Young Elites' by Marie Lu has elements of spying within its fantasy setting.