The film opens on Boxing Day with Megha, a news reporter from Chennai who is writing a story about the mysterious death of a young man named Richard K. Sagayam alias Richie, who was shot dead during a Santa Claus parade in the port city of Thoothukudi. Megha actually knows Richie as he grew up at the reform school her parents used to work at. Megha goes to the port city to investigate the story for her article.

By questioning many villagers, Megha learns that Richie was wrongly sent to the reform school for killing a classmate, even though his childhood best friend Raghu was the culprit. However, Raghu managed to run away from the city and escape the law. The local police then framed Richie for the murder in order to close the case. After witnessing his son beating up another boy at the school, Richie's father, the local priest Father A. K. Sagayam stopped visiting him. After leaving school, Richie returned to his hometown and became the henchman of Isaac Annachi, the don of the city who controlled the local fisherman community. Anything taken from the sea is split between the fishermen and Annachi.

One evening, "Kaaka" Peter, a local fisherman, finds an ancient statue in the sea and tries to sell it by himself to a smuggler from Kolkata. However, Annachi finds out about this and has Richie abduct Peter to find out where the statue is. Peter's best friend, the motorboat mechanic Selvam alias Selvaa, who is in love with Peter's sister Philomena, tries to search for him. As it turns out, Raghu works for the smuggler. Wanting to make money for himself, Raghu steals the statue and returns to Thoothukudi for the first time in years. He secretly meets his widowed mother Radha and promises to take her with him to Dubai, where they can start a new life.

On Christmas Eve, Annachi learns that Peter sold the statue to a smuggler in Kolkata who has allegedly run away to Thoothukudi. He is then also told by Radha that her long-lost son has returned last night from Kolkata. Sensing the connection between the two cases, Annachi sends Richie to retrieve the statue from Raghu. Richie forcefully brings Raghu onto one of his boats, where he tortures Peter in front of him as punishment for going behind Annachi's back. Richie then reveals to Raghu that when he was tormented at the reform school and can never change now. However, after taking the statue, he lets Raghu go but keeps Peter captive. Raghu returns to his mother and tells her to wait for him at the train station the next day so that they can leave the city forever.

On Christmas morning, Raghu manages to track down the house of Murugesh, Richie's friend from the reform home and another member of Annachi's gang. Raghu steals the statue from the house and tries to run away but is captured by Richie and his men. Richie secretly tells Murugesh that he still cares for Raghu and he plans to let his former friend run away with the statue and his mother. However, while driving Raghu to the train station to meet his mother, Raghu starts to get suspicious of Richie's intentions and tries to kill him but ends up getting killed by his childhood friend. Murugesh and their other friends help Richie dispose of Raghu's body in the sea. Radha is shown waiting at the train station for Raghu, who will never come.

Later in the evening, Sagayam is participating in the parade and stops at Annachi's house to bless his own son for the very first time in years. Meanwhile, Selvaa finds Peter's bloodied mask in Richie's jeep, which leads him to believe that Richie killed Peter. He steals Murugesh's gun and shoots Richie while he is dancing in the parade. Murugesh follows Selvaa and guns him down, too. Meanwhile, another one of Annachi's goons finds the statue and runs away with it, while the parade turns into a commotion.

Peter manages to escape his captivity and Murugesh is arrested for killing Selvaa. Both of them and Annachi narrate their story to Megha.