Set in the tumultuous period between June 1932 and December 1933, Runaway Horses follows the journey of Isao Iinuma, a young man deeply influenced by his father's teachings of the samurai code. Isao, driven by a fierce sense of patriotism, becomes the driving force behind a conspiracy aimed at overturning the zaibatsu, the powerful conglomerates he believes have tarnished Japan's spirit, the Yamato-damashii, and betrayed the Emperor's legacy. With the support of Lieutenant Hori, he outlines a bold plan to take out several high-ranking government officials on December 3, 1932.
The narrative reconnects with Shigekuni Honda, a character established in Spring Snow, who now serves as a junior associate judge. His life intertwines with Isao’s as he begins to suspect that Isao might be the reincarnation of Kiyoaki Matsugae, his dear schoolfriend whose tragic story unfolded in the previous novel. Honda becomes increasingly alarmed as he sees Isao heading towards a similarly "picturesque" demise and desperately works to find a way to save him while keeping his internal conflict hidden.
Following the fallout of the May 15 Incident of 1932, which signifies a pivotal moment in Japanese political history, Honda is asked to speak at a kendo tournament on June 16 at the Ōmiwa Shrine in Nara Prefecture. It is at this tournament that he encounters Isao, the son of Shigeyuki Iinuma, Kiyoaki's former tutor who has since transformed into a right-wing figure. This connection piques Honda’s interest further, especially when he notices Isao shares the same three moles as Kiyoaki. The memory of Kiyoaki’s last words, > "I'll see you again. I know it. Beneath the falls," haunts Honda, compelling him to delve deeper into this mystery.
The plot thickens as the story unfolds at the Saigusa Festival where Honda meets Mr. Iinuma, who now runs an "Academy of Patriotism." The academy serves as a breeding ground for Isao's extremist views. After a dinner invitation from Honda, which ends with Isao giving him a copy of his favorite book, The League of the Divine Wind, the bond between the characters deepens, leading to pivotal discussions about historical events that shape their beliefs.
As Isao grapples with his growing ambitions, he organizes his own "Showa League" at a local police station and explores an unsettling camaraderie with other schoolmates, including Izutsu and Sagara. Their discussions constantly pivot towards the justification of political murders and the righteousness of their cause. During a gathering at the Baron Shinkawa's villa, the characters reflect on their respective roles in society, allowing for poignant revelations about honor and legacy.
Isao’s bold actions culminate in an elaborate plan that wavers between idealism and recklessness. As tensions rise within his group, composed of young men set on achieving their vision, Isao’s determination seemingly transitions from a shared endeavor into a need for personal vindication. He finds himself battling feelings of betrayal and cowardice, especially when confronted with the reality that the ties to his father’s ideals may be intertwined with corrupt influences, notably Kurahara.
The story spirals as Isao’s group becomes fragmented amidst doubts and fears. After a sequence of events orchestrated on December 1, the conspirators find themselves arrested, with Isao’s fate hanging in the balance. Honda decides to represent him as a defense lawyer, navigating a complex court case involving political ideologies that spark national outrage and sympathy. Amidst the court proceedings, Makiko, daughter of Lt.-Gen. Kito, enters the narrative, introducing an emotional conflict that further complicates Isao’s motivations and feelings.
As the trial unfolds, Isao’s hope for a better Japan is juxtaposed against the reality of his actions. Despite being found guilty alongside his comrades, the court acknowledges their youth, ultimately leading to their release, though it does little to pacify Isao’s inner torment. The atmosphere of celebration at the Academy of Patriotism soon crumbles when Isao learns that his own father may have betrayed him, eroding the very foundation of his beliefs.
Driven to despair by the duality of honor and betrayal, Isao embarks on a fatal journey that concludes with him taking matters into his own hands. The narrative transitions rapidly to the dramatic climax where Isao confronts Kurahara to avenge perceived slights to his heritage, ultimately culminating in a tragic seppuku that emphasizes the cyclical nature of honor and sacrifice in Japanese culture. The tale of Runaway Horses intricately weaves personal destiny with historical currents, portraying the struggles of youth caught in the throes of ideological fervor and the existential weight of legacy.
