The Last Sister (columbia River #1, Callahan & Mclane, #5)

In the remote coastal town of Bartonville, Oregon, FBI Special Agents Zander Wells and Ava McLane investigate the brutal double murder of Sean and Lindsay Fitch. Sean, a Black man who coached the local high school football team, has been stabbed, dragged outside, and hanged from a backyard tree. His white wife, Lindsay, has been stabbed repeatedly in their bedroom. A hate symbol is carved into Sean's forehead. The crime scene has been contaminated by inexperienced deputies, and Clatsop County Sheriff Merrill Greer initially declares the deaths a murder-suicide before the medical examiner disagrees.

Emily Mills discovers the bodies when Lindsay fails to show for her waitressing shift at the Barton Diner and personally calls the FBI after the sheriff dismisses her concerns about the hate symbol. Emily is a blunt, fiercely independent woman who lives in the crumbling Barton Mansion with her younger sister Madison and three great-aunts: the practical Vina, the sales-obsessed Thea, and the hypochondriac Dory. The aunts are social pillars of the town that bears their family name.

Sheriff Greer reveals a disturbing connection: Emily's father, Lincoln Mills, was hanged in the same county about twenty years earlier, and his convicted killer, Chet Carlson, is in prison. Emily's mother died by suicide shortly after Lincoln's murder, and the sisters were raised by their great-aunts. Neither agent believes the parallel between Lincoln's death and Sean's is coincidental. Emily is overwhelmed when questioned about her father, a subject that triggers recurring nightmares. Her older sister Tara left Bartonville days after Lincoln's murder and has not been heard from since. Zander also notices that Emily and her family are targets of escalating harassment: dead animals on the mansion porch, slashed tires, and broken car windows.

The autopsy reveals both victims had large doses of gamma-hydroxybutyrate (GHB), a drug that induces unconsciousness, in their systems, meaning they were incapacitated during the attack. Sean was already dead from a severed aorta before he was hanged; the killers hanged a dead man to send a message. Lindsay was two months pregnant. Suspicion falls on Kyle and Billy Osburne, local troublemakers. Billy started a bar fight with Sean the night before the murders, and Kyle bears a European Kindred tattoo, a white supremacist prison gang symbol. Kyle reveals Billy was sleeping with Lindsay. Before agents can interview Billy, he flees.

Deputy Nate Copeland, the first officer at the Fitch scene, is then found dead with a gunshot wound staged to look like suicide. His stomach contains beer laced with the same GHB, and gunshot residue on his hand suggests someone else guided his grip on the weapon. Zander suspects Copeland was killed because he witnessed something at the Fitch scene. At a community meeting, Ava argues that Oregon's racist past can go dormant but never truly dies.

Searching woods behind the Fitch home, Zander and Ava encounter Alice Penn, an elderly Bartonville resident known to wander the local forests and coastline, who leads them to skeletal remains hidden under a fallen tree. Dental records confirm the remains belong to Cynthia Green, a nineteen-year-old African American woman from Seattle who vanished during a family vacation on the Oregon coast just two weeks before Lincoln Mills was hanged.

Ava obtains Emily's phone records, which reveal a twenty-minute gap between her arrival at the Fitch home and her 911 call. Confronted at the sheriff's station, Emily explains she found her father's pocket watch in the Fitches' backyard. The watch vanished the night Lincoln was killed, and its reappearance left her in stunned confusion. She also reveals for the first time that she saw Tara at the scene of their father's murder, running through the woods with another person. Emily stayed silent for twenty years to protect her sister.

As Ava drives Emily to retrieve the watch from the mansion, a shooter disguised as a jogger fires at the car, striking Ava in the shoulder. Emily crashes and is treated for a scalp laceration. At the hospital, Ava's fiancé, Mason Callahan, arrives from Portland. Zander, shaken by nearly losing his partner, shares with Emily that he lost his wife and unborn daughter to cancer eight years earlier. Sean's laptop reveals he was researching crime on the northern Oregon coast and had consulted Simon Rhoads, the town's unofficial historian. Simon also gives Emily a file of local historical photos.

Meanwhile, Madison independently uncovers troubling truths about their father. She finds the pocket watch in Emily's drawer and discovers its Latin inscription, "Non Silba Sed Anthar," is a common Ku Klux Klan (KKK) slogan. Conversations with Aunt Dory and Anita, a lifelong Bartonville resident and hairdresser, confirm that Lincoln was widely known as a racist who associated with white supremacist groups.

Zander conducts a video interview with Chet Carlson in prison. Carlson, who had a severe alcohol addiction, explains he pled guilty because he experienced blackouts and believed police when they told him he killed Lincoln. Visitor records reveal that Tara Mills, living near Portland under an assumed name, visited Carlson twice. Zander takes Emily to Tara's home, where they discover she has a nine-year-old daughter named Bella. Tara refuses to explain her twenty-year absence and demands they tell no one about her or Bella.

Isaac, a sullen but hardworking teenager who works at the diner, tips Zander that Billy Osburne is hiding at a girlfriend's house. After a foot chase, Zander arrests Billy, who confesses that Mayor Harlan Trapp paid him to help kill Sean Fitch and then forced him to murder Copeland by threatening Billy's family. Zander examines a group fishing photo from Simon's file and spots Lincoln Mills and Harlan Trapp making a KKK hand sign.

Events accelerate when Aunt Dory reports seeing Tara's car headed toward a coastal overlook where Harlan's vehicle is also parked. The sisters race to the scene and discover Tara came intending to kill Harlan but lost her nerve; he shot her, and she fired back before dropping her gun. Emily crawls along the rain-soaked cliff to reach the wounded Tara, then attacks Harlan with a tetherball chain as he moves to finish Tara off. He shoots Emily in the calf, but Madison arrives and Zander pulls Harlan to safety, arresting him.

In custody, Harlan confesses to crimes spanning two decades. Cynthia Green was killed by his white supremacist group as an initiation exercise. Lincoln Mills refused to participate and threatened to contact police, so Harlan had him hanged and framed Carlson with planted evidence. Sean Fitch was murdered because his research uncovered the connection between Harlan and the group; Sean recognized Lincoln's pocket watch, with its KKK inscription, among Harlan's collection and confronted him. Harlan killed Lindsay because he considered her a "race traitor" and ordered Copeland's murder to eliminate a witness.

Tara, recovering at the mansion, explains that Harlan, who had a sexual relationship with her when she was eighteen, threatened to kill her sisters and mother unless she left town permanently. She spent twenty years in hiding, struggling with fear and addiction. With Harlan imprisoned, she plans to reconnect with her family and bring Bella to the coast.

The novel closes with the three sisters reunited for the first time in twenty years, gathered for tea at the mansion with Zander and the aunts. Madison has stepped up to manage the diner and resolved to stop pushing people away. Zander gives Emily a handmade button bracelet recreating a family heirloom lost when their childhood home burned and asks her to attend Ava's wedding with him. Emily accepts.