Crimson Joy by Robert B. Parker

In this gripping installment of the Spenser series, the seasoned private investigator is drawn into a chilling case involving a serial killer known as "The Red Rose Killer." As the body count rises, each victim is found with a single red rose, a signature that sends shivers down the spine of the Boston community. Spenser, with his sharp wit and unyielding determination, delves into the dark underbelly of the city, navigating through a web of deceit and danger. With the help of his trusted ally, Hawk, and his psychologist girlfriend, Susan Silverman, Spenser races against time to unmask the killer before more lives are claimed, all while confronting his own personal demons.