Detective Cassie Rowan Books in Order

The Detective Cassie Rowan series follows a Liverpool police officer who is sharp, independent, and not especially interested in making difficult work easier for herself. Cassie is drawn to cases where the official answers feel incomplete. That instinct makes her valuable, but it can also put her at odds with colleagues and leave her carrying more than she should.

These are modern police thrillers with a strong psychological pull. The cases involve predatory violence, vulnerable victims, buried histories, and the pressure of working in a force where decisions are watched closely. Liverpool's backstreets, roads, estates, and night-time economy give the investigations a grounded setting rather than a generic crime-fiction backdrop.

Start with Before He Kills Again. A serial predator has attacked several women and left the police with little usable evidence. Cassie goes undercover to get close to the danger, turning the investigation into a tense contest between a detective trying to anticipate a killer and a killer who may be watching her back.

Cassie does not approach the job as a detached observer. She has responsibilities outside work, including a close bond with her younger brother Neil, and those personal demands add weight to the choices she makes on duty. The series lets her be capable and tough without pretending that the job has no cost.

The second book, The Scarecrow Killer, begins with an image Cassie spots beside the M62 after a draining night shift. What looks like a body hanging in the trees opens into a case involving a hit-and-run, a suspicious death, fearful local rumours, and a disturbing pattern that may not be what it first seems.

The mysteries are built around forward motion. Cassie interviews reluctant witnesses, follows connections others dismiss, and deals with the usual headaches of police work, from thin evidence to competing priorities. The stories are dark, but they focus on investigation and character rather than gore for its own sake.

Read the books in publication order, beginning with Before He Kills Again and continuing to The Scarecrow Killer. The cases stand on their own, but the first book gives the clearest introduction to Cassie's methods, family life, and place within the Liverpool police world. Readers looking for a tough, character-led procedural should feel at home here.