“Old spies grow ridiculous, River. Old spies aren’t much better than clowns.”

Or so David Cartwright used to say, but he forgot to add they can be dangerous too, especially if they’ve fallen on hard times—as Diana Taverner learns when the past lands on her desk. An operation carried out during the height of the Troubles laid bare the ugly side of state security, and those involved are threatening to expose details. But every threat hides an opportunity, and the would-be blackmailer is soon being used as Taverner’s solution to a much newer problem.

The O.B. himself is long buried, and has left his library to the Spooks’ College, where it turns out that one of the books has gone missing. Or perhaps never existed . . . River Cartwright has time to kill while waiting to be passed fit for work, and investigating the secrets his grandfather’s library hid seems a harmless activity. But nothing involving the slow horses stays harmless for long.

Louisa Guy is pondering her future, but before making any big decisions, she might as well check River’s not about to come a cropper. Shirley Dander is wondering if the new kid, Ash Khan, is as annoying as she seems. Roddy Ho wants the team to know that his tattoo is a hummingbird, and not, as Lech Wicinski claims, a platypus. And Catherine Standish just wants everyone to play nice.

As far as Lamb’s concerned, they should all be at their desks—when Taverner starts plotting mischief people get hurt, and Lamb has no plans to send in the clowns. On the other hand, if the clowns ignore his instructions, any harm that befalls them is hardly his fault.

But they’re his clowns. And if they don’t all come home, there’ll be a reckoning.