A young boy named Rana, who hails from the kingdom of Kottaipattinam, leaves his family, despite his twin brother Sena pleading him not to do so. The boy soon meets with an accident while rowing in the river and is eventually discovered by some fishermen from the neighbouring kingdom of Kalingapuri, a rival of Kottaipattinam. Rana (Rajinikanth) grows up there and trains in weaponry, and grows up to be a fearless warrior. Due to his fighting skills and bravery, he soon wins the confidence of the king of Kalingapuri, Raja Mahendran (Jackie Shroff), who promotes him as Commander-in-Chief of the Kalingapuri army. The son of Raja Mahendran, Veera Mahendran (Aadhi) shows Rana around the kingdom's mine where the captured soldiers of Kottaipattinam work as slaves. Veera says that this information is known only to a few people. After this, Rana promotes a war strategy to Veera that they release the slaves and have them trained in the army of Kalingapuri. Veera agrees and the slaves are freed. He then gets Raja Mahendran's approval to attack Kottaipattinam. However, during the war, Rana encounters his childhood friend, crown prince Sengodagan (R. Sarathkumar), the son of Rishikodagan (Nassar), king of Kottaipattinam. Instead of fighting, it is revealed that the main motive of Rana's plan was to free the soldiers of Kottipattinam. Immediately signalling an end to the war, he, along with the soldiers disown Kalingapuri and return to Kottaipattinam, much to the disgust of Raja Mahendran and his son, crown prince Veera Mahendran, who swear revenge on Rana for tricking them and betraying Kalingapuri.

At Kottaipattinam, Rana and Sengodagan renew their friendship. Sengodagan introduces Rana to Rishikodagan, who is alarmed on seeing him. Rana also reunites with his younger sister Yamuna Devi (Rukmini Vijayakumar) whom he last saw as a baby and their uncle (Nagesh), who raised her, but soon learns that his mother Yaaghavi (Shobana) is dead and his brother Sena is missing. He soon learns that Yamuna and Sengodagan are in love with each other. He accepts their relationship and decides to get them married, even cleverly convincing Rishikodagan, who was unwilling to get his son married to a commoner like Yamuna. Meanwhile, Rana also falls in love with his childhood sweetheart, princess Vadhana Devi (Deepika Padukone), the daughter of Rishikodagan.

Soon, Sengodagan and Yamuna get married. But following the wedding, Rishikodagan disowns his son for marrying Yamuna despite knowing that the latter does not belong to a royal family. An unfazed Sengodagan immediately leaves the palace with Yamuna. Later that night, a masked man barges into the palace and attempts to kill Rishikodagan. Vadhana immediately goes after him, fights him and gets him captured. Rishikodagan unmasks the assassin who is revealed to be Rana, and immediately throws him into prison, sentencing him to death. An upset Vadhana rushes to the cell where Rana is imprisoned, where Rana tells her why he attempted to kill Rishikodagan.

Years ago, Rana is the younger son of Kochadaiiyaan, the former Commander-in-Chief of Kottaipattinam's army. Kochadaiiyaan is extremely respected in Kottaipattinam for his bravery and is more popular than Rishikodagan himself. So, Rishikodagan jealous of Kochadaiiyaan. One night, when Kochadaiiyaan is returning by ship to Kottaipatinam with his army after buying horses and ammunition, they are attacked by the rival army of Kalingapuri. Kochadaiiyaan defeats them but allows them to return to their kingdom as an act of chivalry. However, the Kalingapuri army, before leaving, poison the food on the ship. The Kottaipattinam army men consume this food, and fall ill.

Despite knowing that he had been tricked by the Kalingapuri army, Kochadaiiyaan immediately rushes to Kalingapuri itself, because it is the only land body close enough to provide medicines to the sick and dying soldiers. He orders Raja Mahendran to provide medical assistance to his soldiers. Raja Mahendran, in turn, cunningly proposes a deal that, if he wants his men to be saved, he has to leave all the horses, ammunition and the sick army men in Kalingapuri as slaves. Only if Kochadaiiyan agrees to this, his soldiers will be nursed back to health. Kochadaiiyan thinks that his men rather be alive as slaves than die from poisoning, and also thinks that when they officially wage a war in the near future, all of them could be easily rescued. So he accepts Raja Mahendran's offer and leaves Kalingapuri all alone. When he returns to Kottaipattinam, the jealous Rishikodagan seizes this opportunity to strip Kochadaiiyan off all respect and dignity and sentences him to death for becoming a traitor to Kottaipattinam by surrendering his army men, horses and ammunition to Kalingapuri. Though all his subjects are dismayed at Kochadaiiyaan being sentenced to death, and his wife Yaaghavi even goes to the extent of publicly rebuking Rishikodagan for his injustice, Rishikodagan stands firm in his decision. Kochadaiiyaan is executed the following morning before Rana's eyes.

The story comes back to the present, with Rana telling Vadhana that he ran away to Kalingapuri, with the intention of freeing the soldiers of Kottaipattinam and to take revenge on Rishikodagan for unjustly killing his father. Vadhana is shocked on hearing about her father's actions and reconciles with Rana. She then pleads with her father to release Rana, but to no avail. Meanwhile, Rana escapes from the prison. When Rishikodagan learns of Rana's escape, he immediately arranges for Vadhana's marriage with prince Veera Mahendran after consulting with an astrologer and learning that his life is at Rana's mercy. Despite the enmity between Kottaipattinam and Kalingapuri, he arranges this marriage with the hope that their united armies and their mutual hatred for Rana can subdue him.

On the day of the marriage, Rana arrives just when the marriage is about to take place. He and the people of Kottapattinam berate Rishikodagan for becoming a traitor and surrendering the whole kingdom of Kottaipattinam to Raja Mahendran for his own personal interests and commitments, which was the same charge that Rishikodagan had placed on Kochadaiiyaan years ago. Following this, a war starts between Rana and the united armies of Kottaipattinam and Kalingapuri. Rana successfully manages to subdue the armies of both kingdoms and along with a majority of Kottaipattinam's army, he kills Raja Mahendran and allows Veera Mahendran to return as he was defeated, reminding him of their friendship. He then fights Rishikodagan and decapitates him.

Finally, as Rana and Vadhana reunite, a young soldier comes towards them riding a horse. This soldier is revealed to be Sena, who looks surprisingly angered, as their father had asked him to protect the king but Rana had killed him, indicating that a fight awaits.

• Rajinikanth as Kochadaiiyaan, Ranadheeran (Rana) and Senadheeran (Sena)
• Deepika Padukone as Princess Vadhana Devi (Voice dubbed by Savitha Reddy)
• R. Sarathkumar as Sengodagan
• Shobana as Princess Yaaghavi Mahadevaki Devi
• Aadhi as Veera Mahendran (Voice dubbed by Kadhir)
• Jackie Shroff as Raja Mahendran
• Nassar as Rishikodagan
• Rukmini Vijayakumar as Yamuna Devi
• Shanmugarajan as Devadhevan
• Soundarya Rajinikanth (Special appearance in "Engae Pogutho Vaanam")
• Deceased actor Nagesh's likeness was used in the film, by means of a 3D model. Actors who sound like him were hired to voice his character while those who had a similar appearance to his, performed the character's performance capture scenes, portraying the role of Rana's maternal uncle.

Development

After the release of Enthiran (2010), Rajinikanth approached K. S. Ravikumar to help complete an animation feature that Soundarya Rajinikanth had begun in 2007. The project titled Sultan: The Warrior had run into problems with its production and Rajinikanth hoped that they could salvage the project by adding a historical back plot which would make the film partially animation and partially live action. Ravikumar then developed a story for fifteen days with his team of assistants and after being impressed by the script, Rajinikanth felt that Ravikumar's story should be an entirely separate film. Thus the team launched a venture titled Rana, to be jointly produced by Ocher Picture Productions and Eros International. The film would have featured cinematographer R. Rathnavelu and music would have been composed by A. R. Rahman. Principal photography, began on 29 April 2011. However, during the first schedule of filming, Rajinikanth fell ill on sets and was admitted to hospital were he was treated for dehydration and exhaustion for over a month, resulting in an indefinite postponement of filming. Further attempts for the film to continue production throughout the year failed. On 23 November 2011, for her maiden directorial project, Soundarya tweeted through her Twitter account, notifying followers to watch out for an official announcement. Following the delay, the team considered making Rana as an animation film but Rajinikanth was insistent that the film would be a live action film. Film producer Murali Manohar then suggested that an animation film could potentially be a sequel to Rana and thus the team began work on Kochadaiiyaan. A tentatively scheduled release period of August 2012 was also announced.