The tenth installment in the Kay Scarpetta series opens on December 6, one year after the murder of Benton Wesley, an FBI profiler and Kay's lover. Dr. Kay Scarpetta, Virginia's chief medical examiner, receives a letter Benton wrote before his death, delivered by Senator Frank Lord, a longtime friend. Benton predicts Kay's behavior with painful accuracy: She has buried herself in work, neglected relationships, and refused to grieve. He asks her to invite Pete Marino, her longtime police colleague, and her niece Lucy for dinner that night. Kay locks the letter in her safe and forces herself to carry on.
Kay learns that a badly decomposed body has been found inside a sealed cargo container at the Port of Richmond, shipped from Antwerp, Belgium. At the scene, the new homicide detective, Rene Anderson, sits in her car with no crime-scene technicians present. Inside the container, Kay finds the dead man propped in a corner, fully clothed but carrying no identification, only foreign coins. Using a forensic alternate light source, she discovers fluorescent French words on a nearby carton: "Bon voyage, le loup-garou," meaning "Have a nice trip, werewolf."
Deputy Chief Diane Bray, a recently hired administrator who has consolidated power over the police department, arrives and confronts Kay. Bray has demoted Marino from detective to uniformed watch commander and installed Anderson as her personal operative. Kay learns Bray is systematically undermining her professional standing and positioning herself for greater political authority.
That evening, Kay honors Benton's request. Marino comes for dinner, and Lucy arrives unexpectedly from Miami with her partner, Jo Sanders. Lucy, an agent with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), is working undercover on a federal task force targeting gun traffickers called the One-Sixty-Fivers. All four read Benton's letter, and the evening dissolves into arguments about grief and loss. The next morning, Kay lashes out at Lucy over callous remarks about death, unleashing pent-up anguish about how Benton's remains were handled.
Kay performs the autopsy on the unidentified man, whom staff call the Container Man. She finds metal sutures from an old jaw fracture and evidence consistent with freshwater drowning; the cause of death is listed as undetermined, the manner as homicide. Lab examination reveals the dead man wore designer clothing, including Armani and Versace. Peculiar long, pale blond hairs found on his clothing are identified as human. Excised skin from his back reveals two bright yellow dots beneath a crudely applied owl tattoo, suggesting the original marks were deliberately altered.
Kay uncovers sabotage within her own office. Her morgue supervisor, Chuck Ruffin, has been using her stolen password to send fraudulent e-mails in her name, declining meetings and running an online impersonation chat room. Kay traces the scheme to Bray, who recruited Ruffin and directed him to undermine Kay's work. Ruffin confesses. Secretary of Health Sinclair Wagner confirms the Governor's Crime Commission is pushing to transfer Kay's office to Public Safety, a move that would give police control over her work.
Lucy's undercover operation in Miami goes catastrophically wrong. During a takedown, Lucy kills two cartel suspects and Jo is shot in the leg and grazed in the head. Pipe bombs are found under both their vehicles. Jo is transferred to a Richmond hospital, and Lucy arrives at Kay's house distraught, fearing the bullet that shattered Jo's femur came from her own gun.
The killer strikes in Richmond. Kim Luong, a convenience store clerk, is found murdered near Kay's neighborhood. A bullet bruised her spinal cord, paralyzing her. The killer beat her face beyond recognition and bit her palms and the soles of her feet. The same pale hairs cover her body, and the ammunition matches that favored by the One-Sixty-Fiver cartel. Kay's time-of-death calculations lead Marino to infer the killer lingered at the scene for hours.
Kay's sister Dorothy arrives uninvited and, at the hospital, effectively reveals Lucy and Jo's romantic relationship to Jo's conservative parents, who bar Lucy from visiting. Lucy flees to New York. Kay persuades her to return home and convinces the Sanderses that barring Lucy is harming Jo's recovery.
Kay and Marino are summoned to Interpol headquarters in Lyon, France, by Senator Lord and ATF liaison Jay Talley. They learn the Richmond murders match eight unsolved killings of women in Paris attributed to a serial killer who calls himself Loup-Garou. The Chandonne family, a centuries-old clan on the Île Saint-Louis, an island in central Paris, secretly runs the One-Sixty-Fiver cartel. The Container Man is believed to be Thomas Chandonne, the family's younger son, who had been embezzling from the cartel. The killer is Thomas's older brother, whose existence the family hid since birth, keeping him confined at home. The yellow dots on the dead man's back were the cartel's membership tattoo, altered by Thomas as he tried to flee. When Thomas's betrayal was discovered, his brother apparently drowned him, placed the body in the container, and boarded the ship bound for Richmond under Thomas's alias.
Talley asks Kay to visit Dr. Ruth Stvan, France's chief medical examiner, to obtain evidence suppressed by a politically compromised magistrate system. Stvan reveals that no lab work was ever done on the Loup-Garou cases and gives Kay swabs and hairs from all eight Paris victims, illegally removing evidence from French jurisdiction.
Kay deduces that the killer has hypertrichosis, an extremely rare congenital disorder causing excessive body hair over the entire body. His deformed, widely spaced teeth account for the unusual bite marks. She theorizes the Chandonnes' lifelong confinement of their son fueled his rage toward women. Trace analysis of diatoms, microscopic organisms found in water, shows those on the container victim's clothing match the Seine, while those on Kim Luong's body match the James River, suggesting the killer ritually bathes in rivers.
In Paris, Kay has a brief sexual encounter with Talley, triggering a furious confrontation with Marino. Struggling with his own grief, Marino speculates that Benton might still be alive. Devastated, Kay requests Benton's autopsy report from the Philadelphia medical examiner; every detail confirms he is dead. The confrontation becomes cathartic, finally allowing both Kay and Marino to express their grief. Before leaving Paris, Kay visits the Île Saint-Louis at night and collects a water sample from the Seine for diatom comparison.
Back in Richmond, Bray is found beaten to death in her bedroom with the same signature as the earlier murders. Anderson confesses she was Bray's visitor the previous evening and reveals the killer likely gained entry by mimicking her distinctive knock. She also confesses to a drug-theft scheme she and Ruffin ran under Bray's direction. Kay identifies the murder weapon as a chipping hammer, a masonry tool with a coiled handle, by purchasing one and matching its patterns to the wounds. Marino locates an empty riverside mansion where the killer has been sheltering after dark.
The killer attempts to break into Kay's garage, then returns to her front door posing as a police officer. When Kay opens the door, she is confronted by a man with an asymmetrical face covered in fine blond stubble. He forces his way inside, and as Kay flees, she grabs a jar of formalin containing his dead brother's preserved tattoo skin and hurls the caustic chemical in his face. Temporarily blinded, the killer staggers after her as she escapes with her Glock pistol, falls on the icy steps, and fractures her elbow. He collapses in the snow, reaching toward her as if begging for help.
Lucy arrives and aims her pistol at the killer's head as ATF agents surround them. Consumed by rage, she refuses to lower the weapon. Kay crawls toward Lucy and speaks calmly, telling her there has been enough killing, that this would not be self-defense, and that Jo is waiting for her. Kay tells Lucy she loves her. Lucy lowers the gun and drops it in the snow. Talley lifts Kay and drives her to the hospital.