Good news, "Slow Horses" fans. "The Secret Hours," by Mick Herron, whose work inspired that Apple Plus TV show, is billed as a stand-alone novel but boasts at least three characters from "Slow Horses," including the sarcastic, short-tempered MI5 boss played by Kristin Scott Thomas.

Her unnamed "First Desk" (fans know her as Diane Taverner, if that's her real name) is involved in more spy-vs.-spy chicanery. A present-day team is investigating three murders at the time of the fall of the Berlin Wall. The deaths were barely noticed then, but now officials want to know what happened and if there was financial malfeasance as well.

Like "Slow Horses," "Secret Hours" delights in complicated plotting that occasionally makes you despair whether you're understanding as much as you should be. Don't worry. You are. But there is so much side-switching and covert maneuvering that you have to trust that Herron knows what he's doing and will explain it all eventually.

As secret witnesses settle scores and spill details to our nominal heroes — low-level wonks Griselda and Malcolm would have gotten out of conducting the investigation if they could have — "Secret Hours" is jam-packed with the kind of acidic insults fans of "Slow Horses" love.

"Of course I'm glad you're not dead," an underling tells the First Desk after a near miss.

"Thank you, Oliver. Perhaps we could work that into a sampler. I could hang it on the hub," is her acerbic reply.

There's wit and suspense on almost every page of "The Secret Hours," where the good guys are bad, the bad guys are worse and the reader is in luck.

The Secret Hours

By: Mick Herron

Publisher: Soho Crime, 365 pages, $27.95.