Iron Flame

The book's climax begins when Jack Barlowe, presumed dead earlier in the year, reappears at Basgiath fully healed and reveals himself to be venin. He sacrifices his own dragon to destroy Basgiath's wardstone, instantly bringing down the college's magical defenses and opening the door for a full venin siege. Riders and the gryphon fliers Violet and Xaden have been secretly training with unite to defend the college as venin forces pour in.

Amid the chaos, scribe Jesinia finishes translating Lyra's journal and reveals the true, previously hidden instructions for activating the wardstone: fire from a dragon of each of seven dens is required, not six as everyone believed. Violet realizes her own dragon, Andarna, belongs to a seventh, previously unknown den. Violet's brother Brennan manages to physically mend the shattered wardstone, and Violet begins pouring her own magic into it to reignite it, quickly nearing exhaustion. Her mother, General Lilith Sorrengail, stops her and instead has Sloane — who has just manifested a rare siphon signet — draw all the magic out of both herself and her dragon to fully imbue the stone, a sacrifice that kills Lilith. With the stone imbued, Andarna and one dragon from each of the six other dens breathe fire on it together, reactivating the wards, killing the attacking wyvern, and repelling the venin assault.

In the aftermath, Xaden pulls Violet aside and confesses what he did during the fight: to kill the venin sage leading the attack and protect her, he drew on magic straight from the earth itself — the same forbidden act that turns riders into venin. He tells her he has become venin himself. The book ends on this revelation, with the wards restored and the immediate siege repelled, but with Violet's mother dead, the true nature of the seven-den wardstone exposed, and the man she loves now carrying the same corruption they've spent the whole book fighting against.

Violet Sorrengail is now a second-year rider at Basgiath War College, bonded to her dragon Tairn as well as a young, unusually gifted dragon named Andarna, whose true nature she has kept largely secret. Early in the year she learns her brother Brennan, believed dead, is alive and a lieutenant colonel leading a rebellion in Aretia against a hidden venin threat that Navarre's leadership has long covered up. Violet is drawn into that rebellion over the course of the book, secretly researching the wards that protect Navarre and uncovering that they were built on incomplete or deliberately falsified information left by the First Six.

Her relationship with Xaden Riorson, stationed at the Samara outpost and secretly organizing weapons smuggling for rebels fighting venin, deepens into a full romance, though his repeated secret-keeping strains their trust throughout the book. Late in the story she learns he carries a second, illegal signet (inntinnsic, letting him sense others' intentions) inherited through his dragon Sgaeyl's original bond to his grandfather. Violet's friendship with Dain Aetos ruptures after she learns he used his memory-reading signet on her without consent, blaming him for squadmate Liam's death, but the two reconcile after Dain turns against the sadistic vice commandant Major Varrish — who had been torturing Violet — and helps kill him alongside Xaden.

Over the year, Violet secures an alliance with Viscount Tecarus (whose niece Cat is Xaden's ex) to obtain a magic-amplifying luminary in exchange for training 100 gryphon fliers at Aretia, and gryphon riders and dragon riders begin uniting against the venin threat. The book ends with a full venin siege on Basgiath after the traitor Jack Barlowe (now revealed as venin) destroys the college's wardstone. The wards are restored only after Violet's mother, General Lilith Sorrengail, sacrifices herself so that Sloane (who manifests a siphon signet) can fully imbue the stone, and after Violet discovers Andarna belongs to a seventh, previously unknown dragon den required to reactivate the wards alongside dragons from the six known dens.

Going into the next book, the wards are back up and the venin attack has been repelled, but Lilith is dead, the cover-up about venin has been publicly exposed, and many riders have defected to Aretia to join the rebellion. Most urgently, Xaden has just confessed to Violet that he drew on magic directly from the earth during the final battle to save her — the same act that corrupts people into venin — meaning he has now become venin himself, an open crisis unresolved as the book closes.