Like many WWI vets, Will Darling struggles to find any kind of employment in England after he gets back from the war. In desperation he writes to a long estranged uncle and reconnects to him just before the man's death. Will inherits a used bookstore which harbors a dangerous secret. The recipe for a weapon even more deadly than gas is hidden somewhere among the 40,000 books and many boxes of papers his uncle left behind-- or so Will must assume, when he begins to receive threatening visits from both the War Office and also a violent anarchist organization. Seemingly by chance, a charming man named Kim Secretan shows up at just the right moment to offer Will his friendship, his help, and maybe more. There's an undeniable sexual attraction between them from the start, but Kim is full of his own secrets, and before long Will isn't sure if he's an ally or an enemy. This is a pulp romance with a satisfying amount of twists and turns. There were a few times in which I think Will fell into slightly obvious traps or showed less agency than he could have; but the high-tension ending gave him time to shine, and show off his own bravery and skill. I've been meaning to start this series forever and I'm pleased I finally made time for the audiobook. I definitely plan to keep reading the series!