This is the sixth instalment in the series about Jackson Lamb and his slow horses.
In Slough House, the MI5 siding, memories are awakened - but unfortunately not good ones. Cathrine Standish is buying alcohol again, and Louisa Guy is digging through the ruins of an old love affair. This time, Lech Wicinski and a prominent lady from the MI5 come to Slough House. At the funeral of the secret service legend, River Cartwright's grandfather, also his father, Frank Harkness, an ex-CIA agent, turns up. Jackson Lamb sends his troop into the field in Wales in search of a well-known traitor - but not everyone returns.
A spy novel in which the author presents the infighting in MI5: there is a struggle for power and everyone tries to cover up anything that might discredit them. Bitter humour and the action jumps from one scenario to another, leaving in suspense what is going to happen in each place.
The characters lack principles, they have no ideal of service to society. Their family life is a farce. The author denounces immoral behaviour, without explicit descriptions.