Onyx Storm by Rebecca Yarros

Here is a summary with spoilers of Onyx Storm

Hours after Iron Flame, Xaden desperately searches for a way to reverse his transformation into a Venin. Seeking answers, he visits Jack in prison. Jack cryptically tells him it’s only a matter of time before Xaden drains Violet and fully succumbs to the change. Unbeknownst to Xaden, Violet overhears everything. Struggling with the revelation, she confides in Imogen, with Andarna helping her process her emotions.

Determined to find Andarna’s breed, Violet pushes forward, though some see her as a symbol of a new rebellion. Tairn remains openly hostile toward Xaden, still angry at him and Sgaeyl. Weeks of patrolling yield no signs of Venin—until they discover that the enemy has infiltrated Basgaith disguised as scribes. Strangely, rather than attacking the wardstone, they focus on breaking Jack out of prison. Even more puzzling, they refuse to harm Violet.

After the battle, Violet and Xaden have a conversation before she meets with the Senarium. Xaden reveals that Sgaeyl has gone silent, sensing that he is now “whole.” He also shares a new ability—he can sense Venin, which means they can sense him too.

The Senarium meeting does not go as Violet had hoped. They still view her as a potential traitor and only a second-year cadet. However, they grant her permission to join a task force to find the elusive seventh dragon breed. Captain Grady is assigned to lead, and they will consider Andarna’s other demands.

Meanwhile, tensions rise among the riders. A factional divide emerges between those loyal to Poromiel and those standing with Navarre. Many who left Basgaith for the rebellion feel they had no choice, while others resent them for it. Violet steps in, urging both sides to focus on their shared purpose: fighting the Venin. However, political negotiations are failing. Matters escalate to the point where Prince Halden, heir to the throne, is brought in—insisting on joining Violet’s mission. Meanwhile, the rebels confront Alaric, Halden’s estranged brother, who has secretly joined the riders. His deception is a ticking time bomb, and the situation becomes so dire that Violet and her allies consider committing treason to take matters into their own hands.

At the same time, the king has had a private conversation with Xaden. He restores Xaden’s title as Duke, grants him his family’s land, Tyrrendor, and secures him a seat at the Senarium.

Violet and her group take action, altering the wardstone to allow fliers to wield magic. She believes she has gotten away with it—until the next morning, when she is charged with high treason and summoned before the Senarium. Through strategic maneuvering, she and her team manage to earn a pardon. However, a new player emerges—Queen Maraya.

Despite the pardon, the second-years in Fourth Wing are sent to the front lines as punishment. During a mission to rescue civilians, they are lured into a trap. Tairn is knocked unconscious, and a silver-haired Venin wielding lightning confronts Violet. The woman, Theophanie, knows a disturbing amount about Violet. She reveals that Andarna is an Irid and warns that Violet and Xaden will eventually fall into their grasp. Violet, however, must choose a side—Theophanie urges her to pick hers.

After the battle, Violet pieces together an unsettling realization. Garrick was able to arrive at the fight impossibly fast. When she confronts Xaden, he confirms that Garrick has two signets. In fact, many rebellion riders—himself included—possess second signets, which increased their chances of survival.

Xaden is sent back to the front lines but writes to Violet, explaining that he’s struggling with his channeling. With him gone, Violet seizes the opportunity to interrogate Jack for more information. When Xaden returns, he finds a temporary solution to being away from Basgaith’s protective wards—becoming a professor. This, however, means he and Violet are forbidden from being together. Aetos, now in charge of Basgaith, ensures they are constantly watched, waiting for them to slip up. As another power move, Aetos also moves into Violet’s parents’ old quarters.

Violet enlists Dain’s help to retrieve a hidden book written by her father. Dain manages to steal it, but it is locked with a word puzzle. Around the same time, Prince Halden arrives to assist in gathering intel on Andarna. It is revealed that he and Violet once dated—until he cheated on her. Xaden, predictably, is furious.

Violet eventually cracks the book’s code, uncovering information about the Second Krovlan Uprising. Her father’s writings direct her to Cordyn, then Deverelli, to find someone named Narelle Anselm and deliver a mysterious gift.

The task force’s first mission ends in disaster—Grady and Aura are killed, though Violet is not particularly saddened by their loss. In the aftermath, Theophanie leaves Violet a chilling message along with a necklace and letter, once again reminding her that she could take her anytime but prefers she come willingly.

Upon returning to Basgaith, Violet demands to form her own squad, a team she can trust. The council agrees but warns that if she fails, Xaden’s titles will be stripped. The team consists of Prince Halden, Mira, Cat, Cat’s cousin, Riddoc, Xaden, and Violet. Their next journey takes them to a land without magic.

There, Violet uncovers six more of her father’s books, all locked with similar codes. While celebrating, they learn that King Courtlyn has taken Halden hostage. Xaden and Violet attempt a rescue, only to discover that Halden’s own guards had been stealing from the treasury. Worse, Halden had gifted Courtlyn valuables that weren’t his to give. Negotiations break down, leading to a violent confrontation where Violet is injured. In a shocking moment, Xaden somehow channels magic—despite there being no magic in the area—obliterating the guards before vanishing.

Back at Basgaith, Mira returns, having visited their grandmother, someone Violet has never met. Mira suggests that one day, Violet should do the same. Meanwhile, Alaric, realizing how badly his brother handled the last mission, comes clean about his identity, choosing to take his rightful place. Halden, enraged, resents losing his role as the “royal” of the group.

Their next stop is Unnbriel. There, they must fight opponents before meeting the ruling council. Violet bests her opponent but yields—only to discover she was fighting the Queen of Unnbriel. The Queen refuses to support their cause unless they return dragons to her island—specifically 12 dragon eggs. During their stay, Violet meets someone with hair strikingly similar to her own, and a disturbing possibility emerges—she may have wielded magic while on land.

Their journey continues to Hedotis, where they are met by an unexpected figure—Xaden’s mother, Talia, now married to one of the rulers. Xaden, abandoned by her at ten years old, wants nothing to do with her but agrees to a meeting to secure an alliance. The council demands a test—both sides must prove their knowledge. During the dinner, Garrick collapses, poisoned. In a dramatic turn, Violet reveals she has poisoned the entire council as well. A standoff ensues until she identifies the source of Garrick’s poison, saving his life. With the council sufficiently rattled, they agree to consider their proposal, though no formal alliance is made.

The squad continues their mission to Zehylna, where they undergo a bizarre trial—each member receives a “gift” and must express gratitude without emotion. All goes well until the last “gift”—an arrow through Traeger’s heart. Though devastated, the group doesn’t react, passing the test. The council agrees to support their war but has no information on the seventh dragon breed.

While resting on an island, the Irids appear, rejecting Andarna and denying any aid in the war. They also hint that Violet’s signet is tied to Andarna. The Irids confirm there is no cure for Venin—each time they channel, a piece of their soul dies. To make matters worse, Riddoc learns the truth—Xaden is Venin.

Back at Riorson House, Violet discovers she can still dream walk. Soon after, they receive devastating news—Theophanie has taken Mira hostage. A plan is quickly formed, but when they arrive, Theophanie brutally slits Mira’s throat. Brennon manages to intervene just in time to offer some aid, and they rush Mira away in the hopes of saving her. Meanwhile, Tarrin takes Mira’s dragon to safety, leaving Violet to face Theophanie alone. Bodhi is there as well, though he's in the midst of his own internal struggle, questioning whether he even wants to be a rider anymore.

During the battle, Violet uncovers a shocking truth—Theophanie is not a lightning wielder like everyone believed, but a storm wielder, just like Violet’s mother. As the fight rages on, we shift perspectives to Imogen, who suffers a heartbreaking loss when Quinn is killed, and to Rhiannon, who is leading her squad through the chaos. Eventually, Violet and Tarrin reunite, determined to put an end to Theophanie.

Elsewhere, Xaden and Sgaeyl have been conspicuously silent throughout the battle. Just as Violet and Tarrin make their move, they are ensnared by a net—at the same time, Xaden and Sgaeyl are also taken down. Struggling to break free, Violet's eyes land on a gift Alaric had given her earlier in the fight—a dagger crafted from marble taken from a sacred temple, one Theophanie cannot step foot in. In that moment, she realizes the truth: Alaric is a precognition. He foresaw this moment, and this dagger is the key.

As the battle intensifies, Andarna returns, but Violet refuses to let her join the fight. Determined to finish things herself, she drives the marble blade into Theophanie just before darkness overtakes her, and she collapses.

We then shift to a Xaden chapter. As he watches Sgaeyl about to be killed, he makes a desperate decision—he channels, unleashing an immense power. In that moment, he feels an eerie sense of freedom, but also the horrifying realization that his soul may be gone. Sgaeyl and Xaden share a cryptic exchange about an unknown plan—one we are not privy to—but Xaden swears that Violet will help because she loves him. He also ominously mentions that "someone owes him a favor." Then, he pleads with Tairn to choose their side. Sgaeyl warns that her decision will determine their fate. Meanwhile, it’s hinted that Xaden has another sibling—one who might have turned Venin.

The book ends with a shocking twist. Violet reappears at Riorson House after being missing for twelve hours, suffering from memory loss. On her finger is a wedding ring, and in her hand, a note in Xaden’s handwriting: "Don’t look for me. It’s yours now."

The others press her for answers, desperate to know where Xaden has gone, especially with dragon eggs stolen and riders dead or missing. Something is very wrong—Tairn, who was perfectly fine after the battle, is now inexplicably asleep. Andarna remains present but remains silent. In a final, chilling moment, Violet turns to Imogen and demands to know what she did. Imogen’s response is simple, yet damning: "What you asked me to."

And with that, we are reminded—her signet allows her to erase and manipulate memories.