Fifty Fifty

The novel opens at the University of Sydney, where an unnamed man stalks the third-floor parking garage, hunting for a confident young brunette resembling the three women he has already killed as the Georges River Killer. His intended target fights back and escapes, screaming past Caitlyn McBeal, an African American exchange student from California. The killer seizes Caitlyn instead. She wakes bound and gagged in a concrete basement with a television, watching police arrest Samuel Jacob Blue for the Georges River murders. Her captor is furious, muttering that things are not yet finished and that he needs Sam, suggesting a partnership between the two men.

Four months later, Detective Harriet Blue, a Sex Crimes officer with Sydney Metro police and Sam's sister, stands on the courthouse steps during Sam's hearings, convinced of his innocence. She and Sam were removed from their mother, who had a drug addiction, at age two and shuffled through foster homes for 16 years, developing fierce loyalty to each other and volatile temperaments. When Prosecutor Liam Woolfmyer taunts Harry about Sam being assaulted in prison, she punches him unconscious in front of journalists. Woolfmyer obtains an apprehended violence order (a court-issued protective order) banning her from the courthouse for nine days. To keep Harry out of trouble, her chief assigns her to a case in the remote New South Wales Outback.

Harry arrives in Last Chance Valley, a town of 75 people inside a massive crater in the desert. Senior Sergeant Victoria Snale, the town's sole active officer, explains that a trucker found a diary at a highway rest stop containing detailed analyses of infamous spree killers, weapon diagrams, and plans for massacring the town. As they descend into the valley, an explosion kills Theo "Soupy" Campbell, the retired police chief, with a propane gas bomb. Elliot Kash, an agent from the Australian Security Intelligence Organisation (ASIO), arrives and assumes command, insisting a terrorist is at large.

Harry and Kash clash over jurisdiction. Kash warns townspeople to watch for Islamic radicalization despite no Islamic content in the diary, and suspicion falls on Zac Taby, a 15-year-old Pakistani boy from the valley's only nonwhite family. Harry challenges Kash to a wrestling match to settle authority and defeats the much larger agent, securing operational command. She later learns Kash lost all four of his friends in the 2002 Bali bombing, an experience that transformed him into an obsessive counterterrorism agent. During the investigation, Harry visits Jed Chatt, the valley's solitary Indigenous resident, a reserved man raising a baby for a relative on the town's outskirts. Harry feels an unexpected calm around him.

In Sydney, Harry's partner, Detective Edward Whittacker (Whitt), attends Sam's hearings and visits him in prison. Sam insists he is being framed. A detective named Tox Barnes, rumored to have a dark past, joins Whitt on the case. The video camera found in Sam's apartment was wiped clean and contained no files, suggesting it was planted. Sam's confession was coerced over a 22-hour interrogation, and seven hours between his arrest and the apartment raid left time for someone to stage evidence. Tox proves the parking garage security guard was not at his post the day Caitlyn disappeared, and they find footage of a stolen dark green sedan leaving at the time of the abduction. Meanwhile, Harry's estranged mother, Julia, threatens to sell a tell-all magazine interview that would damage Sam's case. Harry pays Julia from her savings to decline.

Back in Last Chance Valley, Zac sneaks out of protective custody to steal gold nuggets Harry found in Campbell's desk. He climbs into Snale's car and finds a note on the steering wheel warning him not to get out. Three propane bottles are wired to the driver's seat. Harry tries to replace Zac's weight to prevent detonation, but the timer triggers the blast. Zac is killed, and Harry sustains burns, a broken wrist, and head lacerations.

At the abandoned Pinkerton Hotel, Caitlyn, near death from months of neglect, pretends to be dead and kills a homeless man who wanders into her cell, mistaking him for her captor. Her actual captor chases her through the hotel until she bursts onto the street. Tox finds her and carries her to an ambulance. Caitlyn tells investigators her captor seemed paralyzed after Sam's arrest, as though his partner had been taken from him.

Harry discovers a page carefully removed from the diary. Using pencil shading, Snale reveals a hidden massacre plan for the town's main street. Kash discovers that local man Jace Robit and three associates have booked one-way tickets to Bali and are liquidating assets. Harry and Kash follow them into the desert and find them secretly mining a gold deposit in a cave on land belonging to Jed's family under native title, a legal recognition of Indigenous ancestral land rights. The men deny writing the diary. Mick, the town bartender, arrives with a revolver and shoots two of the men dead before Harry subdues him.

The diary's true author is Bella Destro, the mayor's university-aged daughter. She points Harry's own gun at her and reveals Mayor Dez strapped to a chair with a homemade bomb at his neck. Bella explains that since age 14 she was forced to be her father's accomplice in drugging and photographing children during his wilderness leadership camps. She reported the abuse to Campbell, a teacher, and another parent, but no one acted. Bella detonates the bomb, killing her father, then tapes a second device to Harry's throat and marches her into the crowded pub. She offers a choice: Harry detonates her own bomb to save the town, or Bella triggers a larger device hidden elsewhere. Harry pushes the button, but the device malfunctions. Before Bella can reach her own detonator, Snale fires a rifle shot from the upper-floor railing, killing her.

In parallel, Whitt traces the planted camera to a shop where footage shows a purchaser far too tall to be Sam. Police release photographs of suspects whose fingerprints were found at the Pinkerton Hotel. One, Regan Banks, believed to be Caitlyn's captor and the man who framed Sam, enters Harry's apartment, where Tox waits as part of a trap. They fight savagely until a neighbor's interruption allows Regan to stab Tox twice. Collapsing, Tox scratches Regan's ankle to collect DNA under his fingernails and balls his fist shut. Whitt arrives and seals an evidence bag around Tox's hand. Tox dies in the ambulance and is resuscitated. The DNA matches Regan Banks.

Regan's history emerges through his recollections. He and Sam met as 16-year-old foster children. When Sam refused to help rob a veterinary clinic, Regan broke in alone and murdered the vet. Sam anonymously reported the crime, leading to Regan's 15-year imprisonment. After release, Regan tracked Sam to the university, killed three brunettes, and planted evidence to frame him. Whitt follows a hunch to the Georges River and finds Regan wounded on a dark pier. Regan confirms that he framed Sam and that Sam is innocent, but escapes into the river under police gunfire.

Before leaving the Outback, Harry stops at Jed's house and places a gold nugget on his table, informing him the deposit on his land is worth millions. Jed asks her to stay. She refuses. At the Sydney airport, Whitt delivers devastating news: Tox is critical, Regan escaped, and Sam died in a prison fight that morning. Harry receives a cold text from Julia, who intends to keep the money. Something inside Harry shifts permanently, and the dark half of her nature wins. She resolves that Regan will not be caught by colleagues who would spare his life. He will be hers. She walks away from Whitt and disappears into the crowd.