Banging out a prequel to a thriving mystery series, ten books strong, doesn’t sound like marketing wisdom, but “The Infirmary,” #11 in the DCI Ryan roster but set in Newcastle in 2014, stands strongly on its own feet. DCI Ryan (note the lack of first name) investigates a particularly vicious serial killer who has just added the police investigator to his victim list. Ryan is a wonderfully drawn, stolid sheriff, and his supporting cast of officers comes alive vividly. The pace rattles along under firm authorial control and the plot is clever in that detailed, police procedural way we’ve grown to love. Ross’s style is engaging with frequent sprinklings of humour or irony. I read the book in a couple of sittings and now look forward to catching up with the full series.