Even within what you might think is a circumscribed sub-genre, that of police procedural mysteries, different narrative styles present themselves. We all know the rebel hunters of killers, such as Bosch and Rebus, those flawed fireballs, but there’s another style in which the hero is very ordinary and the pleasure of the read is in the sifting of clues and detailed investigation. DI Nathaniel Caslin, the York-based center of J M Dalgliesh’s now-six-book strong series, is a stolid, equable man fascinated by his job and unstoppable in turning over every stone. No histrionics, just patient labour. Yet the latest book, “The Sixth Precept,” is anything but slow. Caslin and his team (a most believable set of characters) soon find themselves in a hideous spiral of serial killings, and the killer’s calling cards – chopping off a finger and leaving a lotus leaf – are just the beginning of the bizarreness of the crimes, all thoroughly mystifying. Told in a calm, clear style that works a treat, Dalgliesh never misses a beat as he doles out a tricky plot that left me entranced. A single night’s read for sure.