In Pursuit of the Proper Sinner (2004)

　　Lynley investigates the death of Nicola Maiden and Gerry Cole who were beaten to death while out camping. Nicola's father Andy Maiden is a retired police officer but neither of her parents know, or will admit to knowin...展开g, who Cole is and thought she was seeing Julian Britton. Andy believes she was killed as a means of getting back at him and offers to go through his old files. The investigation reveals that Nicola worked for Martin Reeve, the owner of an escort agency. She had recently quit and set off on her own. Andy had also put him away once, for 10 years, leading to the break-up of Reeve's marriage. When another murder occurs, it sends the investigation in a different direction involving a theft and blackmail. Sgt. Havers finds herself demoted and back in uniform for having shot a flare pistol at a senior officer who had put a child in danger. Lynley manages to get her assigned to the case and hopes she will take the opportunity to rehabilitate her reputation and her career.