The first installment in the Lyonesse Trilogy opens at the Washington, DC, wedding of Mark Trevena's older sister Blanche to Brigadier General Ricker Thomas. On a balcony, Mark, a former CIA operative who owns an ultra-exclusive kink club called Lyonesse, discusses unnamed plans with his twin sister Melody, a CIA deputy director. They observe Tristan Thomas, the groom's son, a decorated former soldier in his late twenties recently returned from four deployments to Carpathia, a fictional Eastern European nation wracked by insurgency. Mark insists Tristan is essential to his scheme; Melody warns that people are not pawns.
Weeks later, Tristan narrates in the first person as he interviews for the position of Mark's personal bodyguard at Lyonesse, a glass-and-steel building on an island in the Potomac River. Aimless after leaving the army, he carries a Distinguished Service Cross and unnamed trauma. Mark explains the role: a near-constant shadow requiring proximity at all times. Tristan learns that Lyonesse collects information rather than money as membership dues, using personal secrets and professional intelligence for leverage, including blackmail. The revelation both disgusts and fascinates him. That night, he reveals he is a 29-year-old virgin whose military career ended because he killed his best friend, Aaron Sims. Unable to face another purposeless day, he accepts the job by midnight.
At Lyonesse, Tristan meets key staff: Goran, the head of security and a former Marine; Dinah, the club manager; Sedge, Mark's quiet assistant; and Andrea, the sharp-tongued treasurer. The basement server room houses Lyonesse's most critical asset: members' secrets. Goran hints that Mark's previous bodyguard, Strassburg, had a sexual relationship with Mark. During a consent review in Mark's office, Tristan admits that wax play, the erotic dripping of hot wax on the body, and breeding kinks, fantasies of impregnation and ownership unrelated to literal procreation, are not aversions but arousal triggers.
Tristan's first evening in the club immerses him in a world of power exchange. He watches Arjun, a Dominant (the controlling partner in kink play), lead his submissive (the partner who yields control) Evander on a leash. Mark tells Tristan there is romance in surrender. One evening on the rooftop, Mark kisses Tristan, soft and tasting of juniper and citrus, then breaks the kiss, explaining it as a gift: Tristan had confided that the thing he most hoped for while deployed was a kiss. The gesture consumes his thoughts for days.
Mark's operations reveal Lyonesse's reach. One morning, Tristan finds Isabella Beroul, a submissive from Montreal, tied to Mark's desk. Mark has sex with her while Tristan watches, making deliberate eye contact while climaxing. Learning that Mark and Strassburg had a domination-and-submission arrangement, Tristan begins considering offering himself as Strassburg's replacement.
On a flight to Singapore, Tristan has a violent nightmare about killing Sims, reliving the moment in vivid, distorted detail. Mark wakes him with sharp commands, ordering him to breathe, and tells him that heroes are make-believe: What Tristan did was not heroic but necessary. Emboldened, Tristan offers himself as Mark's submissive at the hotel. Mark refuses, admitting intense desire but insisting Tristan does not understand what submission to him entails: degradation, control, being used like a toy. Mark adds that a relationship would derail his plans. He also uses Tristan as an alibi during the trip, disappearing for hours on an unexplained errand, deepening Tristan's unease. Meanwhile, Tristan's father warns that intelligence agencies suspect Mark of selling classified information, but Tristan dismisses the concern.
The turning point comes at Morois House, an ancestral Trevena property in Cornwall, where Mark locks himself in the library with scotch for two days. Tristan discovers a facedown photograph of a man wearing what appears to be Mark's silver wristwatch and deduces this was someone Mark loved who is no longer present. On the third morning, Tristan kneels at Mark's feet, and this time Mark does not refuse. He takes Tristan's virginity on the library floor and spends the day using him throughout the house with escalating intensity. Afterward, Mark explains he avoids intimacy with club submissives because sex and information do not mix. They sleep in each other's arms, and for the first time since Carpathia, Tristan has no nightmares.
Back at Lyonesse, they formalize their arrangement. Tristan chooses "hazel" as his safeword, the agreed-upon word to stop any scene, inspired by a tree they sat under in Cornwall. Their days settle into an intense rhythm of domination and submission. For Tristan's birthday, Mark gives him an elaborate wax play scene that culminates in a shattering orgasm. Tristan cries afterward, not from pain but from the certainty that he is irrevocably in love. Mark also enlists Tristan in covert operations, including sabotaging a Senate vote on a space exploration bill by poisoning a senator and manipulating other votes.
During Lyonesse's annual open house, armed operatives sent by Drobny, a Slovakian businessman with ties to Carpathian rebels, attack the club. A feint draws Tristan to the basement while the real assault targets the main hall. Tristan races back to find a knife buried in Mark's shoulder, kills the attacker, and shields Mark's body. As Mark falls asleep that night holding Tristan's hand, Tristan whispers that he loves him. During recovery, Tristan discovers two wedding bands in Mark's drawer and learns from Sedge that Mark is engaged to Isolde Laurence, daughter of banker Geoffrey Laurence, with the wedding two months away. Mark reveals the engagement has been publicly announced and in the works for four years. Devastated, Tristan ends the sexual relationship. Mark asks him to collect Isolde from Ireland aboard his yacht, the
Philtre D'Amour, since his wound prevents travel. Tristan calls the request cruel but relents when Mark insists Isolde is the most important thing in the world to him.
At Cashel House on the Irish coast, Tristan prepares to despise the woman marrying Mark. The moment Isolde opens the door, his resentment dissolves. Aboard the yacht, they establish a routine: mornings sparring in the dojo, where Isolde proves devastatingly skilled with a honeysuckle-hilted knife Mark gave her, and dinners where she gradually opens up. She wanted to become a nun, but her father pushed her toward business; she now works for an art and antiquities firm. Mark calls Tristan most mornings, instructing him to woo Isolde as his proxy, but does not call Isolde directly. She is shocked to learn of Mark's stabbing, revealing they have not seen each other in two years.
Tristan discovers Isolde has nightmares and goes to her each night, ordering her to breathe as Mark once did for him. They confide in each other: Tristan about killing Sims, Isolde about a parallel grief she will not explain. Physical attraction escalates until a wave pitches them together during sparring; they climax against each other through their clothes. After two days of avoidance, Isolde reveals the engagement is arranged: a transaction to merge Laurence Bank's financial power with Lyonesse's information network. Fidelity is expected only after the wedding. They have sex for the first time in the yacht's chapel, and Tristan discovers a dominant side of himself he has never experienced.
For the remaining week, they hide the affair from the crew. Tristan discovers he loves both dominating Isolde and being dominated by Mark, fantasizing about all three together. Mark informs Tristan by phone that Chloe Sims, Aaron Sims's sister, has come to Lyonesse looking for him, filling Tristan with dread. As Manhattan approaches, Tristan ends the affair: he loves Mark, cannot betray him, and must remain a trustworthy bodyguard. Isolde agrees flatly that it was just fun, but her composure betrays her pain. She tells him this week was the best of her life.
At the Manhattan marina, Mark waits on the dock. He takes Isolde's hand and calls her his queen. As they walk toward the cars, Sedge quietly tells Tristan he should have checked for cameras on the yacht. Tristan realizes with horror that Sedge knows about him and Isolde, and that Mark will likely learn the truth. Mark looks back over his shoulder and calmly tells Tristan to come along, as they have much to discuss. The story continues in the next installment of the trilogy.