Paranjyothi, a brave and rustic youth has a meteoric rise in Pallava cavalry. After a short war in the North, Mahendra Pallavar makes him the Commander of the Kanchi Fort. The crown prince Narasimha Pallavar (aka Mamallar) is impressed with Paranjyothi and the two soon become intimate friends. Narasimha Pallavar confides in Paranjyothi about his ardent love for Sivakami, the daughter of Aayanar, the leading sculptor of the empire. Paranjyothi, aware of Mahendra Pallavar’s disapproval of the relationship, is in a dilemma.
Mahendra Pallavar successfully keeps apart Mamallar and Sivakami. The royal charioteer, Kannabiran, acts as the go-between carrying the lovers’ messages. But the long period of separation makes Sivakami believe in the crafty Buddha-bikshu Naganandi’s allegations about Mamallar. Hence she decides to ignore Mamallar’s missive to remain at her forest residence. Naganandi, Aayanar, Sivakami and her aunt leave their forest residence and head to Nagapattinam. Naganandi claims that he will arrange for Sivakami to perform there before an august audience.
En route they meet Gundodharan. Though an apprentice with Aayanar, he is in reality a Pallava spy. The spy chief Shatrugnan had commanded him to observe the goings-on at Aayanar’s residence. Gundodharan clears Sivakami’s misconception about Mamallar. He also hands over to Naganandi a message from his disciple.
An annoyed Naganandi reads the message which states King Durvineethan of Ganga Nadu is invading Kanchi as per Naganandi’s instructions. As Naganandi had given no such instruction, he realizes that there is treachery afoot.
So he asks Aayanar and family to stay in a deserted viharam at Ashokapuram and heads to an unknown destination. On the fourth day, Aayanar and Sivakami observe the Ganga Nadu army fleeing with Pallava soldiers pursuing. Mamallar and Paranjyothi pass through the Viharam in hot pursuit of Durvineethan. Mamallar sees Sivakami standing outside the viharam but does not pause to speak to her. His charioteer Kannabiran however stops to inform Sivakami of Mamallar vanquishing Durvineethan at the Pullalur Battle and promises to tell Mamallar that Sivakami had sought his forgiveness.
Meanwhile, Gundodharan returns to Ashokapuram and relates Mamallar’s heroic feats at the Pullalur Battle. He also finds and shadows Naganandi and overhears him saying that the Thirupaar Kadal dam may be breached that night on account of the cyclone. A shocked Gundodharan shadows Naganandi and observes Naganandi using a spade to breach the dam embankment. While he tries to close the breach, he hears Mahendra Pallavar’s voice in the dark commanding him to save Aayanar and Sivakami. Gundodharan pushes Naganandi into the dam and hastens to Ashokapuram.
The flood waters reach Ashokapuram ahead of Gundodharan. Aayanar and his family climb to the upper storey of the viharam. Gundodharan manoeuvres a boat to the viharam. Mamallar, eager to rescue Aayanar and Sivakami, leaves his army at the banks of the South Pennai River and rides to Ashokapuram. He joins Gundodharan to rescue Aayanar and his family.
Those in Gundodharan’s boat reach Mandapapattu village. The villagers accord the group a warm reception. The group spends three days at Mandapapattu when Mamallar and Sivakami get the rare opportunity to spend time together and declare their undying love for each other. Mamallar promises her that she would be his Queen Consort when he ascends the throne. Sivakami’s soul-stirring dance concert endears her to the villagers.
Meanwhile, Mahendra Pallavar accompanied by Shatrugan leaves in search of Mamallar. So does Paranjyothi accompanied by the Pallava forces. Paranjyothi traces Mamallar at Mandapapattu and escorts him back. Soon they receive Mahendra Pallavar’s missive instructing them to hasten to Kanchi.
Mahendra Pallavar and Shatrugnan meet Gundodharan and reach Mandapapattu village. Gundodharan also informs Mahendra Pallavar that Naganandi had arrived at that village and had tried to stab Mamallar several times. Gundodharan then escorts Mahendra Pallavar and Shatrugnan to the monastery in which Aayanar and Sivakami are staying. The shrewd Mahendra Pallavar surmises that Naganandi must be still inside the monastery.
Mahendra Pallavar hands over the lion insignia, which would give the bearer instant access to the Kanchi Fort and the senior-most officials of the Pallava Kingdom, to Aayanar. As expected, it falls into the hands of Naganandi.
Mahendra Pallavar then sends Aayanar off with Shatrugnan to search for his boat and isolates Sivakami. He then informs Sivakami of Naganandi’s unrequited love for her and his attempts to kill Mamallar because of that. He tries to influence her to free Mamallar from her love so that he could arrange Mamallar’s wedding with the Pandya princess. This marriage would make Pandyas his allies and help him win Pulikesi. Sivakami vehemently refuses.
Meanwhile, Naganandi shows the lion insignia to Mahendra Varmar’s charioteer, Kannabiran, and asks him to hasten to Kanchi. Though Mahendra Varmar observes this from a distance, he does not prevent the reluctant Kannabiran from riding away with Naganandi. Naganandi, on reaching Kanchi, disguises himself as an injured Pallava spy and gains entry to the Ministers’ Council with the help of the lion insignia and informs them that Mahendra Pallavar has been imprisoned by the Chalukyas. Mamallar, in his anguish, prepares to lead the army out of the Kanchi Fort, attack the Chalukyas and liberate Mahendra Pallavar.
Unfortunately for Naganandi, Mahendra Pallavar himself arrives just then and imprisons him. He then gives a rousing speech motivating the Ministers’ Council and the chieftains of the provinces and forts, enlisting their support for his plans. A guard rushes in and informs the Court that a cloud of dust heralding the arrival of the Vatapi army was seen at the horizon. Mahendra Pallavar commands Paranjyothi to escort the chieftains of provinces and forts outside the Kanchi Fort and demolish the last surviving bridge. The Kanchi siege begins.