Nani, Sudeep, Samantha
Nani is a young man who specializes in making fireworks. He lives in a house opposite micro artist Bindu, who also runs Project 511, an NGO. Nani is in in love with Bindu for two years and has been constantly showing his love for her. Bindu too loves Nani back but hides her love from him.
Sudeep is a multi-millionaire industrialist who is also a womaniser. He had even killed his wife for her money. One day, Bindu goes to Sudeep's office to see if he would like to donate money to her NGO. Sudeep sees Bindu and immediately lusts for her, and calls her into his office. Bindu, unaware of Sudeep's true intentions, tells him all about her NGO, he donates 15 lakhs to it. Bindu thanks Sudeep, who invites her for lunch.
At the restaurant, Bindu sees Nani and his friends installing fireworks across the pool. Sudeep notices that Bindu keeps staring at Nani and becomes jealous. Later, when Sudeep and Bindu stop at a market, Nani also comes and walks with Bindu. Sudeep follows them the whole time. That night, Bindu works late and she needs an escort to go home, so she calls Nani who comes to her office and walks her home. At this point, Nani gives Bindu an idea to help finish a necklace she was working on and Bindu is finally ready to confess her love towards Nani. But just in front of Bindu's doorstep, and just after Nani drops her, Sudeep kidnaps him and takes him to a graveyard, where he beats him mercilessly. He tells Nani that he loves Bindu. Nani tells Sudeep that if he goes anywhere near Bindu, he will kill him. Enraged, Sudeep strangles Nani, right after Bindu tells Nani she loves him through a text and a phone call. Upon hearing that Bindu loves him, Nani dies, but is then reborn as a fly.
After adapting to his new life, Nani comes across Sudeep, then recollects his past life and wants to take revenge on Sudeep. He keeps following Sudeep around, irritating him repeatedly. Meanwhile, Bindu is grieving the death of Nani, and Sudeep is still trying to make Bindu love him.
One day, Sudeep calls Bindu to her office and asks her to come to Delhi with him to meet the Education Minister, who is planning to nationally recognize Bindu's NGO, she agrees. Nani notices this and causes Sudeep to meet with an accident while he is driving to the airport. Sudeep, lying injured, sees Nani write the words "I will kill you". From that point, Sudeep becomes paranoid about the fly, and tries all means to ensure Nani does not enter his house.
Later, Nani comes across Bindu, who is crying. Nani uses Bindu's tears on her desk to write out, "I am Nani". He then shows Bindu that it was Sudeep who killed him, and that he was reborn as a fly. Bindu realizes Sudeep's true nature and teams up with Nani the fly, using her skills as a micro artist to make Sudeep's life miserable. Bindu discreetly allows Nani to enter Sudeep's house, and Nani wreaks havoc on him, including burning all of his wealth. A terrified Sudeep then consults Tantra, a sorcerer, who tells him that Nani, whom he had killed, was reborn as a fly and is planning to kill him. Tantra performs a 'homa' in Sudeep's house to kill Nani. But Nani escapes and causes a short circuit, leaving Tantra dead and Sudeep unconscious.
Next morning, Sudeep finds out that Bindu and Nani are working together to kill him. Enraged, Sudeep brings Bindu to his house and starts abusing her. He also clips Nani's wings and stabs it fatally. A dying Nani then sacrifices its life by jumping through a lighted matchstick, inflaming itself and entering a loaded cannon, which fires up and kills Sudeep.
Bindu, grieving the fly's death, makes a necklace using the only remainder of Nani the fly- its wing. While going to work, an eve-teaser abuses her, only for a fly to attack him. This fly is revealed to be Nani, again reborn to protect Bindu forever.