Senthil

A reckless townman tries to mend his thug ways ends up resurrecting himself and proves to be worthy of the world, in the eyes of the same people who chased him away.

Inspired by real-life incidents that led up to the sensational 1987 Opera House heist, Thaanaa Serndha Koottam recounts the story of a group of con artists who swindled rich businessmen out of a fortune by posing as CBI officers.

A poor Venu works at a roadside shop and loves Jyothi, his employed neighbour. Before Venu gets a chance to express his love to her, she meets with an accident and he is arrested.

Family and personal life is messed up for a cool dude, when suddenly his possessive wife doubts/links up a relationship with a girl from his office.

Nachiappan (Nassar) is a wealthy and successful Indian American restaurateur based in Los Angeles, USA. He has two sons - Vishwanathan "Visu" (Prashanth) and Ramamoorthy "Ramu" (Prashanth) - who are identical twins. They both are medical students and spend their evenings helping out their father alongside the restaurant's chief cook, Juno (Senthil). One evening, when Visu & Ramu go to the airport to do their lunch supply to KLM staff, Visu sees an Indian family from Chennai - Madhumitha "Madhu" (Aishwarya Rai), her younger brother Madhesh (Raju Sundaram), and their grandmother Krishnaveny (Lakshmi) - having some problems with the immigration authorities. Visu pitches in to help and learns that they just flew in from India so that Krishnaveny can undergo a surgery to remove her brain tumor. After many confusions, the trio meets with Ramu also (Visu vanishes out of sight and the trio start following Ramu when they see and mistake him for Visu). The twins arrange for the three to reach their host. Krishnaveny is admitted in the hospital where Visu works as a resident doctor and the surgery is performed. Visu soon realizes that Krishnaveny is paralyzed as she was operated on the wrong side of her brain due to a mix-up with another patient. He appeals aggressively to the doctors and has the error corrected by another surgery, then spearheads an angry fight for compensation. The hospital compensates US$2 million to avoid a court case. Due to these actions, Madhu soon falls in love with Visu. Krishnaveny soon realizes that Madhu and Visu are in love and extends the family's stay in the USA. However, Nachiappan objects to the romance as he wants his sons to marry identical twin girls. In a flashback, it is shown that Nachiappan had an identical twin brother Pechiappan, who lives in Karaikudi and is a simpleton. They used to run a restaurant together with Nachiappan as cook and Pechiappan as cashier. Pechiappan made mistakes in bills and Nachiappan's wife corrected him. They both married for love in their youth, but Pechiappan's wife Sundarambal (Raadhika) tortured and abused Nachiappan's pregnant wife Meiyaththa (Geetha) (as a punishment for correcting her husband publicly) so badly (Meiyaththa was feeling breathless and Sundarambal refused to let Pechiappan to go to the market to get her a soda. Nachiappa was at the market, buying groceries for the restaurant.) that the latter died (After she went to the market to get her own soda) after giving birth to Visu and Ramu. Nachiappan eventually left the house along with Visu and Ramu to prevent Pechiappan and Sundarambal from separating over Meiyaththa's death (the whole society blames Sundarambal for Meiyaththa's death and Sundarambal wants Pechiappa to split the property and leave, or else she will leave Pechiappa). Their mother wailed that as twins, if they had married sisters, they would have supported each other.. This is the root of Nachiappan's demand that Visu and Ramu should marry sisters. Krishnaveny decides to solve the problem by lying to Nachiappan that Madhu does have an identical twin named Vaishnavi, who was raised separately in an orthodox Brahmin household. The reason for their separation is claimed that "having twins would bring bad luck on their family". Nachiappan falls for the lie and leaves for India along with Visu, Ramu, Juno, Krishnaveny, Madhu and Madhesh in order to "meet" Vaishnavi and fix the marriages of Visu and Ramu with Madhu and Vaishnavi respectively. as Vellaiappan (S. V. Shekhar) is Madhumita's dad. Krishnaveny convinces Madhumita to spend some time with Ramu. She will arrange for the wedding with Visu and when done, they will tell Nachiappan that Vaishnavi has died or eloped. Krishnaveny has Madhu pose as Vaishnavi, who contrary to Madhu, is very demure and traditional in nature. The plan is that Ramu will reject a "desi" girl like Vaishnavi. Ramu immediately falls in love with Vaishnavi, unaware that she is Madhu. Madhesh uses sophisticated computer 3D images to give the impression that Madhu and Vaishnavi are 2 different girls. Nachiappan insists that both weddings take place on the same date. So, Krishnaveny's plan goes for a toss. Meanwhile, Pechiappan, whose marriage with Sundarambal has worsened due to the latter's inability to have children, attempts suicide. Nachiappan rescues him and hatches a plan to unite both the families through Visu's and Ramu's marriage plan. Nachiappan impersonates Pechiappan and leaves for Karaikudi, where with his business sense and practical nature, he rescues Pechiappan's failing restaurant business and eventually reforms Sundarambal as well (He defends Sundarambal when the villagers pressure Pechiappan to marry again, as his wife is barren. He says his wife tolerates his flaws and so, he will tolerate hers). Pechiappan takes Nachiappan's place and stays with Visu and Ramu. Eventually, Madhu, realizing that Ramu is madly in love with her alter-ego, decides to stop acting as Vaishnavi as she feels she is hurting Ramu's as well as Visu's feelings through her act. Visu too finds out in parallel that Vaishnavi does not exist (That she was a computer generated 3D image by Madhesh). Enraged, Visu and his family immediately leave Madhu's house, but Ramu tells him that Madhu had lied due to her love for him and convinces him to reconcile with her. Ramu further manages to convince his father, unaware that he is his uncle Pechiappan, to get Visu and Madhu married. When Nachiappan realizes the truth and finds out that Visu and Madhu are getting married, he immediately rushes to Chennai with Sundarambal and stops the wedding. At this point, it is revealed that both Nachiappan and Pechiappan had impersonated each other in order to reunite both the families. Sundarambal manages to convince Nachiappan to get Visu and Madhu married since Madhu, by posing as Vaishnavi, had done the same thing that Nachiappan and Pechiappan did. Visu and Madhu get married and the movie ends with their reception, with Madhesh entertaining the couple and guests with computer-generated special effects.