Law’s narrative is well-traveled, the opening chapters of his first novel intensifying the claustrophobic, violent atmosphere that permeates his literary thriller. Flashing back to the culmination of a case a few years earlier, we meet Lieutenant Danielle “Dan” Lewis from England’s Special Investigation Branch, Loss of Life Division. Dan has been working off and on for almost ten years to bring cold-blooded killer Chris Hamilton to justice. The opening scenes are ferocious and brutal as Dan fights for her life; the damage Hamilton inflicts on Dan sets the tone for much of what is to come. In the aftermath of that confrontation, Dan--now plagued by panic attacks--wishes more than anything that her sister, Charlie, and her father could see it as clearly does: all of her blood and bruises, “as if her clothes were still torn and her back still raw.”

Still reeling from Hamilton, Dan is asked by Commander Roger Blackett of the Portsmouth Unit to the investigate the strange suicide of Whiskey Walker, an old naval colleague who Dan knew back in basic training. Walker has hanged himself by the neck on board HMS Tenacity, one of the very special class of nuclear hunter-killer submarines that run out of Devonport. Both Blackett and the Royal Navy’s top brass want an investigation conducted that can establish the whereabouts of every member of Tenacity’s company. Walker was the duty technical senior rate on board, and his death occurred the same evening his wife, Cheryl Walker was beaten, raped, and murdered, her body left near a remote parking lot up on the moor.

By concentrating on the procedural aspects of investigation as opposed to the crimes, Dan plunges deep into the smooth, black floating mass of the HMS Tenacity in a tense race against time to try to outwit and outmaneuver a killer. Dan is warned by her colleague, Master at Arms John Granger, that there’s already a lot of stress on the ship. She must maintain a supportive role in providing information on Whiskey‘s death, or information that might support the investigation into Cheryl’s murder. Dan is positive that Cheryl’s killer is onboard, a notion reinforced by Felicity Green of National Crime Agency, who is convinced that the motive for Cheryl’s murder lies somewhere inside her life, tangled up with her children, or with a lover, or a husband who was rarely home.

Moody and stylish, Tenacity posits a familiar scenario in which a maniac is perhaps duplicating the crimes of Chris Hamilton. And while we've seen this exact setup countless times before, somehow Law makes it all seem fresh. With Dan’s mind gaining momentum, she runs through the maze of options, each possible route throwing up more questions, more uncertainties, and more challenges. Her first barrier is Tenacity’s gruff Commanding Officer Melvin Bradshaw, the “Old Man” who lays down the law and makes it known that Tenacity is a male-only vessel and that Dan is far from welcome. Dan learns to keep her profile as low as possible and keep out of the way as best she can, and to stop herself from turning to John for support. All the while she begins to question herself about what she actually knows: the note from Walter isn’t conclusive, and the location of his suicide could mean nothing at all.

The tension of the novel builds slowly, the atmosphere becoming as suffocating and stultifying as Tenacity’s tightly-knit, darkened passages. As the reality of her situation begins to kick in, Dan finds herself ensconced in her own sleeping area in the “bomb shop,” mostly feeling angry and uncomfortable. As the perpetual heat causes a state of constant perspiration in an atmosphere made from equal parts oil and stale air, kindly Aaron embarks on a mission to keep Dan protected from the Old Man, who seems to be deliberately acting to turn the crew against her. Placed in an impossible situation, Dan begins her quest to conduct her interviews and find out where people were and who they were with before Walker was found hanged. She is soon confronted with a mix of dour uncooperative sailors who wish to say nothing and have nothing to say, along with Chief Officer McCrae, whose hostility and anger hides a deeper misogyny that becomes a necessary nightmare lurking in Dan’s future.

In the fragile ecosystem of a submarine, where emotions often run high and where “the submariners are good at keeping secrets but not from each other,” Dan’s questions are mostly lost in the noise of the heave, of men shouting and grunting, and the daily clamor of the submarine’s operations that seems to absorb her words “like shadows falling into darkness.” How much do Tenacity’s crew really know about what happened to Cheryl Walker? Questions linger in Dan’s mind as she thinks back to her cabin in the Portsmouth dockyard, to the lock box placed there, and the secret images trapped inside it that are impossible to share--images that link Dan to Hamilton and also to Cheryl’s violent death.

The pace in Tenacity never lessens as Law accelerates Dan into a collision course that is expected considering the crew’s myopic, insular nature. Beyond the horrific physical descriptions of torture, Law delves deeply into Dan's psyche, detailing the black unseen terrors that gambol on the periphery of her mind, and a humiliating attack that has eclipsed and erased every other event in her life. The deceptive tranquility of submarine life, the camaraderie of the men who have known one another for so long and who give up so much, the sanctity of the Royal Navy, and a monster that perhaps lurks on the decks of Tenacity, are all shattered in a brutal ending in which events spin wildly out of control and Dan once again finds herself fighting for her life.