The Deep Dark Sleep is the third book in the Lennox series set in 1950s Glasgow. Lennox is still haunted by his time as a commando during the war and has wound up in Glasgow, working as a private investigator rather than return to his native Canada. Through guile and favours and he manages to navigate the criminal underworld of the ‘three kings’, while also maintaining friendships with policemen prepared to help him with his cases. As such, he’s the logical choice of PI for those who need difficult cases solved involving some criminal element. In this outing, he’s hired by the twin daughters of the most feared and successful criminal in the city before the war to discover whether a body dredged from the Clyde is their father, and by a solicitor acting on behalf of an American movie star who is being blackmailed over some explicit photographs. While the latter case seems relatively straightforward to resolve, the former soon turns deadly. Someone it seems is prepared to kill to keep the mystery of Gentleman Joe Strachan a mystery. Lennox is an engaging character, 1950s Glasgow is well portrayed, and Russell keeps the tale moving at pace. The twin threads, plus Lennox’s slow romantic pursuit of his landlady, is compelling and entertaining. However, while each thread is interesting, their entwining as the story unfolded felt like a somewhat clunky plot device that didn’t ring true. The result was an enjoyable tale that progressed to a seemingly inevitable and staged conclusion.