Heartless Sky is the seventh installment in Caroline Peckham and Susanne Valenti’s Zodiac Academy series, a romantasy saga set in the magical Fae kingdom of Solaria. The series follows twin sisters Darcy and Tory Vega, raised in the mortal world, who discover on their nineteenth birthday that they are the true heirs to the Solarian throne. Their parents, the late King and Queen, were murdered when the twins were infants, and the crown was seized by a Council of four powerful families. In The Awakening, the twins are thrust into Zodiac Academy, an elite institution where they must master their newly awakened magic while lasting the vicious hazing of the four Celestial Heirs: Darius, Caleb, Seth and Max. The Heirs, groomed since birth to inherit the throne collectively, view the Vegas as usurpers and orchestrate a campaign of bullying designed to drive them out.

Subsequent books deepen both the political conspiracy and the romantic entanglements. Tory experiences an “enemy to lovers” romantic arc with Darius, despite his initially cruel bullying; when he first professes his feelings, she rejects him, unleashing a “Star-Crossed” curse that forbids proximity or intimacy between them. (This curse is dissolved at the end of Fated Throne as a side-effect of Darius’s fatal bargain). Darcy, meanwhile, falls into a forbidden romance with Professor Lance Orion, a teacher at Zodiac Academy. Darcy and Orion initially hide their relationship, but when it is uncovered, Orion pleads guilty to having coerced Darcy and goes to prison. He believes he is protecting her reputation and claim to power by doing so, but this decision leads to a significant loss of trust within their relationship. The false charges and imprisonment also set the stage for the “power shaming” Orion endures in Heartless Sky.

Lionel Acrux, Darius’s father, is the primary antagonist in the series. He engineered the deaths of Tory and Darcy’s parents and has been scheming to eliminate their claim to power ever since they returned to Solaria. Lionel’s desire to rule as sole king of Solaria has led him to ally with both the Nymphs (the traditional enemies of the Fae) and with forces of dark magic. Lionel was previously romantically involved with Stella Orion (Lance Orion’s mother) and the two of them engaged in dark “shadow magic” rituals to heighten Lionel’s powers.

These rituals involved manipulating Clara Orion (Lance’s sister and Stella’s daughter); in The Shadow Princess, Orion learns that Clara is trapped in the magical Shadow Realm and he and Darcy bring Clara back from the Shadow Realm. However, what returns is actually Lavinia, an ancient and powerful magic being who has taken possession of Clara. The fact that Lavinia is possessing Clara’s physical form and keeping her spirit trapped in torturous limbo is not revealed until Fated Throne; when Orion realizes what is happening, he kills Clara’s physical form so that her spirit can be at peace. However, this act does not eliminate Lavinia, and she becomes even more powerful once she assumes her own independent form.

Lavinia’s backstory is also revealed in Fated Throne, via a series of magical visions. Lavinia was once an ancient Nymph princess who lusted for power; she allied with one of Lionel’s ancestors in a plot to unseat an ancient Vega queen (one of the twins’ ancestors) but he betrayed her. Lavinia’s spirit still craves the throne she believes she was promised, hence her alliance with Lionel. In Fated Throne, Lionel enacts a coup and claims the throne, promptly enacting a series of oppressive policies that lead to the formation of the rebel movement (Fae who actively work against him). The climatic events of Fated Throne set the stage for Heartless Sky. On Christmas Day, Lionel prepares to execute Darcy and Orion in a large public arena, but various allies come to their aid, leading to a fierce battle (in which Tory destroys Lionel’s hand). It is also during this battle that Lavinia curses Darcy (setting the stage for significant plot events in Heartless Sky).

While these events are occurring, Darius is absent: a prophecy warned him that he must urgently intervene to prevent the imminent death of a Vega princess. While the battle rages in the arena, he makes his way through a magic cave where he is offered the choice to prevent Tory’s death at Lionel’s hands. Darius can save her by agreeing to a deal: Tory will live and all magical bonds that impact either of them will vanish. However, after one year, he will pay for the deal with his life. Desperate to save the woman he loves, Darius agrees. This bargain is a major driver of the conflict in Heartless Sky, especially since Darius conceals it for most of the plot. While they achieve some positive outcomes in the Christmas Day battle, the twins and their allies cannot defeat Lionel and are forced to flee. As Heartless Sky opens, the twins, the Heirs, Orion, and their allies have taken refuge with the rebels, regrouping to plan their next efforts to destroy Lionel.