A young girl who is unable to sleep asks her father to tell her a bedtime story. Although reluctant at first, he tells her a story of a fly named Nani.

Nani is a young man who specialises in preparing fireworks. He is in love with his neighbour Bindu, a micro artist who runs Project 511, a non-governmental organisation (NGO). Bindu also develops feelings for Nani though she does not express them. Seeking to raise money for her NGO, Bindu visits the office of a rich, powerful industrialist named Sudeep, who also finds her attractive. He befriends her, donates ?1.5 million (US$23.03 thousand), and gains her trust. Sudeep sees Nani as a rival and plans to kill him. One night, Nani helps Bindu to finish a piece of micro art—a locket made from a pencil. While returning home, he is kidnapped by Sudeep, who kills him, making his death look like an accident. Unaware of the incident, Bindu proposes to the dying Nani by telephone; it is the last thing Nani hears before he is reincarnated as a housefly that cannot remember its previous life.

The fly's memory is triggered when it encounters Sudeep and Bindu. Sudeep asks the heartbroken Bindu to accompany him to New Delhi to meet the education minister; if she can impress the minister with a presentation about the NGO, he might help it gain national recognition. The fly causes Sudeep to have an accident on his way to the airport and writes "I will kill you" on the windshield; this makes Sudeep paranoid. The fly, who sees Bindu mourning Nani's death in her bedroom, reveals itself to be Nani by writing on the desk with her tears. It conveys the circumstances of Nani's death to Bindu, and they join forces against Sudeep. The latter's obsession with the fly affects his professional and personal life. In a chain of events, his money is burnt to ashes, leaving him almost penniless.

Sudeep learns from a sorcerer that Nani is reincarnated as a fly and seeks revenge. Sudeep arranges to kill Nani but the fly escapes and causes a short circuit, killing the sorcerer and leaving Sudeep unconscious. Nani and Bindu assume Sudeep is dead but he is saved by his business partner. Sudeep is enraged when he learns that Bindu is helping the fly. Sudeep kills his partner to collect a ?7 billion (US$107.49 million) insurance policy.

Sudeep takes Bindu to his home and Nani follows them. Nani seriously injures Sudeep with a needle. The latter clips Nani's wing and fatally stabs him with the same needle. Nani jumps through the flame of a burning match then into a loaded cannon, which fires. The projectile passes through Sudeep and hits an oxygen cylinder, which explodes and kills him. Bindu takes the fly's wing and makes an amulet with it. One day when travelling to work, an eve teaser bothers her; Nani, again reborn as a fly, attacks him with a needle before announcing his return.

The young girl is impressed with the story of the fly her father narrates.

• Sudeep as Sudeep
• Nani as Nani
• Samantha Ruth Prabhu as Bindu
• Adithya as Sudeep's business partner
• Thagubothu Ramesh as a thief who loves Bindu (Telugu version)
• Santhanam as Pottu Govindan, a thief who loves Bindu (Tamil version)
• Chandra Sekhar as Tantra, a sorcerer
• Noel Sean as Nani's friend
• Srinivasa Reddy as Sudeep's personal assistant
• Sivannarayana Naripeddi as a temple priest
• Devadarshini as Bindu's sister-in-law
• Hamsa Nandini as Kala (cameo appearance)
• Crazy Mohan as a Malayali veterinarian (cameo appearance, Tamil version)

Origin, scripting and casting

The idea for Eega originated in the late 1990s in screenwriter K. V. Vijayendra Prasad's mind. At that time, he was joking about a housefly seeking revenge on a human in a conversation with his son S. S. Rajamouli. Prasad later developed the idea as a script for an English-language film set in 1830s America, in which an African-American boy dies in an attempt to free his family from slavery and is reincarnated as a fly. After completing Maryada Ramanna (2010), Rajamouli reconsidered the concept after thinking of directing a film that was distinct from any other. He decided to make Eega a bilingual film in Telugu and Tamil – each scene including speech was filmed twice, once for each language. The Tamil version, titled Naan Ee, was Rajamouli's directorial debut in Tamil cinema. The film was presented by Daggubati Suresh Babu of Suresh Productions.

For the first time in his career, Rajamouli began casting after the script was completed because he felt the story required actors who were suitable for the roles. Nani, the protagonist, was the first of the three of the main cast members to be chosen; he completed filming his scenes in 25 days. Samantha Ruth Prabhu, the second actor cast, was signed as the female lead. Rajamouli chose Sudeep to play the fly's human adversary after being impressed with the actor's performance in Rann (2010), and cast rapper Noel Sean as Nani's friend in the film. Sudeep drew inspiration for his role as the villain from the 1983 Kannada film Bhakta Prahlada; he was portraying a character he considered to be a "bad guy" with "grey shades" rather than an antagonist.

The script was doctored by Rajamouli's brother, S. S. Kanchi, while Janardhan Maharshi and Crazy Mohan wrote the dialogue for the Telugu and Tamil versions respectively, marking their first collaboration with Rajamouli. James Fowlds was initially chosen as the film's director of photography, but was replaced by K. K. Senthil Kumar due to creative differences and scheduling conflicts. M. M. Keeravani composed the film's soundtrack and score, Kotagiri Venkateswara Rao edited the film, Ravinder Reddy was its art director, and Rajamouli's wife Rama worked on the costume design.

Production of the film began with a formal launch ceremony on 7 December 2010 in Hyderabad. The original version was filmed over a six-month period and cost nearly ?110 million; Rajamouli felt the quality of the material was poor and started again. The film's final budget was estimated at between ?260 and ?400 million.

Filming and post-production

Principal photography began on 22 February 2011 in Hyderabad; ninety percent of the film was shot at Ramanaidu Studios in the city. A sequence was filmed at Sri Sita Ramachandra Swamy Temple in Ammapally near Shamshabad, in early March 2011. Scenes with Nani, Samantha, and Sudeep were filmed during the first shooting schedule, which was completed on 16 March. Shooting was disrupted in April by an ongoing labour dispute between film workers and producers. Rajamouli considered moving Eega out of Hyderabad if the strike continued. Filming continued in Kokapet in early September 2011, and principal photography was completed in late February 2012 as post-production began.

According to Rajamouli, the film unit consulted a 3D video of the storyboard before shooting a scene each day. After the filming of each scene was completed, the editing and re-recording procedures were done with simple greyscale animation. An Arri Alexa camera, a prime lens, and Sco