"A novel"--Jacket.

"The books that inspired ... Slow horses, the Apple TV+ original series"--Back of jacket.

"David Cartwright, long buried, has left his library to the Spooks' College in Oxford, and now it turns out that one of the books has gone missing. Or perhaps it never existed. Now River, once a 'slow horse' of Slough House, MI5's outpost for demoted and disgraced spies, has some time to kill while awaiting medical clearance to return to work, and investigating the secrets of his grandfather's library seems a harmless activity. But nothing involving the slow horses ever stays harmless for long. Over at the Park, MI5 First Desk Diana Taverner is in a pickle. An operation carried out during the height of the Troubles revealed the ugly side of state security, and those involved are threatening to expose details. But every threat hides an opportunity, and Taverner has come up with a scheme in which the would-be blackmailer is a solution to a much newer problem"--