The fourth book of ponniyin selvan, titled Manimagudam, follows the events that lead to the coronation of Arulmozhivarman as the Chola king. The book begins with the arrival of Vandhiyathevan and Azhwarkadiyan in Thanjavur, where they meet Kundhavai and inform her about Arulmozhivarman's survival and return. Meanwhile, Nandhini and the Pazhuvettarayars plot to assassinate Aditya Karikalan and usurp the throne. They also try to manipulate Madhuranthakan, the son of Uttama Chola, to join their cause. The book also introduces new characters, such as Aniruddha Brahmarayar, the chief minister of the Chola empire, and Vanathi, the niece of Nandhini and the love interest of Arulmozhivarman. The book ends with a dramatic twist, as Aditya Karikalan is murdered by a mysterious assassin, and Arulmozhivarman is proclaimed as the heir apparent by Aniruddha Brahmarayar.