This study aims to identify a clear instance of non-peaceful power transition in Iran's history (specifically during the Kayanian era) by drawing on evidence from the Shahnameh and other authoritative historical texts. The goal is to challenge the idealized narrative of a smooth and peaceful succession. The research adopts a text-based historical analysis approach. It compares the accounts found in Ferdowsi's Shahnameh with older sources, such as Dinavari's Akhbar al-Taval, while also considering the broader intellectual and social contexts of the time—particularly the influence of the Shu'ubiyya movement. Evidence relating to the king's (Kay Kavus) behavior, the role of warriors (especially Rostam), and the succession process of Kay Khosrow has been collected and analyzed. The findings reveal several unprecedented actions that point to a collapse of royal authority. These include Rostam openly insulting the king and killing his wife (Sudabeh) without any reaction from Kay Kavus, as well as Rostam—not the king—issuing the order to attack Turan and sending the spoils of war to Zabolestan. Such events indicate that power had effectively left the court. Furthermore, the ambiguity and contradictions in the sources regarding Kay Kavus's fate—ranging from voluntary abdication to deposition and imprisonment—alongside Dinavari's explicit report that he was imprisoned for the rest of his life, strongly suggest that a non-peaceful transfer of power did take place. It appears that the narrators, influenced by the Shu'ubiyya movement, deliberately reshaped the events into a peaceful narrative. Their aim was likely to present Kay Khosrow as an ideal, powerful, and successful Iranian ruler—a model of superior Persian governance—by smoothing over the more problematic aspects of how he came to power.