Radiant Sin

The fourth installment in the Dark Olympus series, Radiant Sin is set in Olympus, a modern city-state governed by the Thirteen, a ruling council whose members each hold titles drawn from Greek mythology, such as Zeus, Hera, Apollo, and Hermes. The city is shielded from the outside world by a mysterious boundary, and political power is concentrated among legacy families whose lineages stretch back to the city's founding.

Cassandra Gataki is the sharp-tongued executive assistant to Apollo, one of the Thirteen. She comes from a disgraced legacy family. Twelve years earlier, her parents attempted to exploit a secret, ancient clause in Olympus's laws that allows anyone who kills a member of the Thirteen to claim that person's title. The Thirteen had her parents killed and covered it up as a car accident. Since then, Cassandra has supported her younger sister, Alexandra, while planning to eventually escape the city. Despite her deep distrust of the Thirteen, Cassandra has developed an undeniable attraction to Apollo over five years of working for him. Apollo, for his part, has been quietly in love with her for years but has never spoken up, unwilling to pressure an employee who has already suffered at the hands of the powerful.

The central conflict begins when Minos, a mysterious outsider who recently arrived in Olympus with his household, leverages intelligence about a supposed external threat in exchange for citizenship. Zeus grants the request because the city's protective boundary is secretly failing. Apollo is ordered to stay close to Minos and uncover his true intentions. When Minos hosts a weeklong house party at his country estate, Apollo asks Cassandra to pose as his girlfriend and accompany him, needing her keen ability to read people. She initially refuses, knowing the public association will invite scrutiny, but Zeus intervenes with a financial offer. Cassandra negotiates aggressively, securing $1.4 million and safe passage out of Olympus for herself and Alexandra.

To sell the fake relationship, Apollo takes Cassandra to the Dryad, an exclusive restaurant, for a public date. Their staged kiss deepens into something genuine, leaving both shaken. They travel to Minos's country estate, which formerly belonged to Hermes, a fellow member of the Thirteen. Apollo sweeps their room for surveillance devices and contacts Hector, his tech specialist, who remotely hacks the house's security system to disable all cameras and microphones.

The guest list is eclectic and strategic: Six members of the Thirteen attend, most with companions. Notable guests include Hermes; Aphrodite with her on-again, off-again partner Adonis; Artemis and Hephaestus, who share a date named Atalanta; Eurydice Dimitriou, Demeter's youngest daughter; Charon Ariti, representing Hades's interests; Pan, the owner of the Dryad; and Minos's household, including his foster sons Theseus and the Minotaur and his children Ariadne and Icarus.

Minos orchestrates nightly party games, including a hedge maze competition and hide-and-seek, that seem designed to control and observe his guests. He pulls Apollo aside for a private drink, making veiled threats about Cassandra's safety and suggesting Apollo marry one of his children. Cassandra theorizes that Minos is attempting to match his children with single members of the Thirteen. After the house's cameras are disabled, the Minotaur appears in a hallway and warns that with no surveillance, no one's safety is guaranteed.

The escalating danger and forced proximity push Apollo and Cassandra past their boundaries. Cassandra reveals that Hermes is her ex-girlfriend and proposes making the sexual aspect of the fake relationship real. Apollo agrees, and their physical connection proves intense and emotionally charged. Despite growing closer, both silently accept that their relationship has a deadline: Cassandra is leaving, and Apollo will not ask her to stay.

Hermes privately warns Cassandra to leave the party, insisting it is dangerous, but refuses to explain why. Cassandra declines, unwilling to abandon Apollo. During the hide-and-seek game, Apollo and Cassandra use the distraction to search the locked third floor. They find Ariadne's bedroom unlocked, her laptop open with Minos's email account still logged in. Apollo forwards hundreds of emails to Hector for analysis. Cassandra suspects Ariadne deliberately left the information accessible, a theory reinforced when Ariadne catches them and cryptically says she is glad she was "right about" Apollo.

The situation turns violent when Pan is found unconscious in the library with a head wound, a bloodied marble tortoise hidden nearby. Minos dismisses the attack as a drunken accident. Cassandra urges everyone to leave, but the other members of the Thirteen refuse, displaying an attitude of invulnerability that enrages her.

The true scope of the plot emerges when Cassandra follows Hermes through a secret passageway and overhears her speaking with Minos. Hermes provided Minos with knowledge of the assassination clause and insider access to Olympus in exchange for information about Minos's benefactor, a mysterious woman who represents the real external threat to the city. Cassandra learns that Pan's attack was a mistake by Icarus, who was supposed to target Aphrodite; that Atalanta is tied up in the basement to prevent her from interfering; and that Minos's foster sons intend to murder members of the Thirteen and claim their titles. Hermes catches Cassandra eavesdropping and warns that no one will believe her, echoing the dismissal Cassandra faced 12 years ago when she tried to report her parents' murder.

Apollo believes Cassandra immediately. They rush to warn the remaining guests but discover that Artemis has gone to the duck pond with the Minotaur and Hephaestus has left for the garage with Theseus. Apollo refuses to split up, declaring he loves Cassandra and would let the city burn before putting her in danger. They reach Artemis first, arriving just as the Minotaur strikes. Their shouted warnings give Artemis enough time to fight back and escape by swimming across the pond. At the garage, they are too late: Theseus has beaten Hephaestus to death. Apollo tackles Theseus and they fight brutally until Cassandra grabs a tire iron and strikes Theseus repeatedly, giving Apollo the opening to knock him unconscious. Theseus regains consciousness and formally invokes the assassination clause, naming Cassandra as his witness and claiming the title of Hephaestus.

Ares, formerly Helen Kasios and Zeus's sister, one of the Thirteen, arrives with a security team and takes control of the scene. Apollo brings Cassandra back to his penthouse. Minos has leaked the existence of the assassination clause to the press, making the Thirteen's most closely guarded secret public knowledge. Any ambitious citizen now knows they can theoretically murder their way into power.

Apollo assumes Cassandra will take her money and leave as planned. Instead, a phone call with Alexandra changes everything. Alexandra reveals she is happy in Olympus, with friends, a graduate program, and a new internship with Demeter's company. She tells Cassandra to stop sacrificing herself and to stay for Apollo. Hermes also visits, apologizing and insisting cryptically that everything she did was for Olympus.

At an emergency meeting of the Thirteen, Theseus is officially recognized as the new Hephaestus because the assassination clause is now public and Zeus cannot execute him without provoking a crisis. Aphrodite volunteers to marry the new Hephaestus as a distraction to redirect public attention. Apollo returns home expecting Cassandra to be gone and finds her waiting. She tells him she is staying because she loves him and chooses to build a life with him. He confesses he has loved her for four years, and she tells him to propose in a few months. The novel ends as the city enters a volatile new era, with the story of Aphrodite and the new Hephaestus continuing in the next installment, Cruel Seduction.