“Thankam” means gold in Malayalam which is an appropriate title for the movie. It revolves around a group of gold brokers who go to distribute gold to Mumbai and find themselves involved in a murder case. The movie is revolving around the investigation of the case and retraces the journey the victim to took.
Muthu and Kannan get 2kg of gold from a merchant. They plan to go via Coimbatore to Mumbai to take the gold and sell it to merchants. Kannan takes the car and was planning to take a few more gold on the way and eventually sell 8kg of gold in Mumbai. The merchant was also called to Mumbai to foresee the sale. But, on the way, Kannan encounters a police checkpost and flees the scene. The police follow him and take him into custody. Kannan had forgotten the key. As a result, police thought he was stealing the car. He called Muthu and asked him to come fast to the police station to bail him out.
Muthu travels to the police station to show the key, to prove they are innocent. But cops start questioning them about what his relationship was with the suspect, Kannan. They kept asking Kannan about another person in the car that the cops saw, but Kannan denied any such person. Kannan eventually had to pay some ransom to the sub-inspector and was released from the police station.
But, Kannan indeed had someone in the car, who ran away with the gold he had in the car. The next day, he called him and received the gold back. Following that, Arul, who is a friend of Kannan dropped him at the bus station. From there, Kannan went to Mumbai.
The merchant reached the hotel where Kannan said he had booked the room. But even after calling many times, Kannan didn’t answer the phone. Muthu also tried but no luck. Police started looking into the matter. After a few days, police found a dead body in the hotel Kannan was staying and Kannan’s ID was found on the floor. Muthu was called by police with this info on loudspeaker which Kannan’s wife heard as well. Both of them went to Mumbai to identify the body. Kannan’s wife confirmed the body.
Mumbai police brought in the merchant, Muthu, Kannan’s wife Keerthy, and Kannan’s dad for questioning. They asked questions as someone was killed. They said that if they bear the expense, then the police will come to Kerala to investigate the matter. This was agreed upon by Muthu.
Upon reaching Trichur, police started confirming the stories that Muthu and others told them. Upon questioning, they found out that Arul had not come in for questioning. So, the Police went to Tamil Nadu to ask questions to him. Upon finding him and asking questions, Arul didn’t answer anything conclusively. The police were sure that Arul had to have something to do with it. They try to take him to question but Arul flees the scene. Later, Muthu tries to withdraw some money for food, when he encounters Arul taking money out of an ATM. That’s when the police grab him. He is taken to Mumbai for questioning.
Meanwhile, cops find out that two people had called Kannan’s phone. One was Arul while the other was some girl in Tamil Nadu. They track her down and she says the phone is used by someone named “Vicky”. Vicky is a criminal who is in jail. They go and ask him questions but he does not answer any questions. Later after forcing him, the police get to know that he called Abbas. Meanwhile, cops tell Muthu that there is something weird from the CCTV footage. It almost seemed like Kannan was bringing someone and deliberately hiding him from the camera.
Abbas was then searched, and found in some areas in Tamil Nadu. Police searched his house and found Kannan’s bag but Abbas was not there. Abbas’s wife told that he has not come back for a few days. They told her that he is planning to sell 2kg of gold and then move to Sri Lanka to live with his new girlfriend. Upon hearing that, Abbas’s wife agrees to help the police. She calls him and persuades him to come to the bus station. When she reaches there, there is an auto rickshaw that picks her up to take her to Abbas. They reach the theatre and tell her to go inside and wait. Upon going inside, Abbas meets her at the seats. A police officer sees this and tries to apprehend him but he kicks the shit out of them. But Muthu was right outside. He nabs him and gives him to police officers.
After questioning him, the police get a few more details. The doubt that police officers had, is confirmed. Kannan did indeed stage himself as being stabbed so that they can share the 2kg of gold that Kannan had. It seems Kannan was in huge debt. Only Kannan, Abbas, and Arul knew this. All of them know each other for a long time. Abbas said he was planning to take gold and later share it.
Police tell Muthu that Kannan was in a huge debt. And he tried to suicide so that all the people who gave him the loan, will forgive him. Muthu upon hearing this didn’t believe him.
Arul later is released and meets with Keerthy. He confirms that Kannan indeed had the plan to kill himself in the end. He had only told Arul. He also gave Arul a gold locket which was what Kannan wears. He was instructed to give this to Kannan’s wife and tell her the same.
Keerthy later stopped at a temple, while going back to Kerala. She put the coin in the hundial. And the movie ends as the gold coin falls with other coins in that.