Three murders happen on a moving train. Murder on the Orient Express, an Agatha Christie classic, inspired the crime thriller.
Internationally famous Indian shooter Nadiya (Kavya Madhavan) catches Sauparnika Express, a train on its inaugural run between Chennai and Mangalore. She is murdered en route, is not the only victim on the train. A famous dancer, Thulasi and a television reporter, Shreya Mariya, are also killed. When investigators fail to solve the mystery, the case is turned over to Sharafuddeen Taramasi (Suresh Gopi), IPS, an encounter specialist from the Railway Anti-Criminal Task Force (RATs)
RATs discovers that 3 murders are not inter-connected rather it was sheer coincidence that it happened all in one same night. Thulasi, the dancer was murdered by the coach attendant on orders of his boss, the division manager Vijayabhanu (Suresh Krishna). Vijaybhanu was husband of Thulsi's sister and felt mad love in her. He approached her numerous times, which was rejected by Thulsi. She threatened to disclose the approaches of Vijayabhanu to the world, which made him to kill her, before she reaches home.
Shreya, the reporter was behind Alexander Chempadan IPS, who was a Police officer indulged into smuggling. Shreya was following Alexander who boarded the train, to make a string operation about the goods he carry on board. However Alexender overhears Shreya's mobile conversations, which make him suspicious and discovers her identity card from her bag. He arranged a professional killer to kill her, when train reaches near Salem, who threw her from moving train, which kills her.
However the most complicated was murder attempt of Nadiya. She appeared to be brutally raped with teeth marks on her body and nerve to brains being cut. When police reached her coupe, they thought she was dead, by doctors on next coupe confirmed that she has not died, which made immediate transfer to hospital. Sharadudden goes behind Nadiya and finds that she along with her identical twin sister Nadira were orphans and raised by eminent dancer Subhadra at her academy. Nadira grew up as a professional dancer, while Nadiya became acclaimed shooter. Their step mother Subhadra died, leaving all properties to twin sisters which are now managed by Aadi Lakshmi (Urmila Unni), their manager. Nadira's marriage was fixed with international acclaimed musician Zia Musafir, son of Subhadra's discipline and loyalist Ustad Ghulam Musafir. Ustad was not happy with the investigation, especially its chief officer Sharafudden due to several reasons.
While doctors ruled that, chances of Nadiya recovering from her coma state is very less, Ustad even argues Nadira to sign consent paper for mercy killing, which she refuses. While at home, someone tried to attack Nadira from behind, who ran away when she bited hardly on his hand while trying to entangle her. While investigation continues, they discovered that Nadiya had called to Academy's phone number hours before her death. They also found that, the train made a technical stop at Coimbatore nearly 2 hours which was announced on board. The investigators wondered why Nadiya didn't choose to travel to her academy at Palakkad which is just 40 mins from Coimbatore station, rather waiting for train to reach Palakkad after 2 hours. Connecting pieces, they realized, someone had used Academy's official car and entered into Coimbatore car park area. Sharafudden concluded that Aadi Lakshmi's brother killed Nadiya, which Nadira opposes while talking to her privately. Sharafudeen conforted with Nadira that, if not Aadi Lakshmi's brother, it should be Zia Musharaf who might done this, by taking a break from his world tour, as he have information that Zia was not in Bahamas on the day Nadiya was killed and was in India as per Emigration records. Nadira said, its not right and affirmed Zia will never do that, as she spoke to him on that night calling his Bahamas number.
Sharafudden decides to take all the suspects to Chennai for conducting a scientific Narco-analysis test along with Nadhiya who is in state of coma, by taking the same train- Sauparika Express.
While in train, when Nadira was standing near to door, Sharafudden comes there for a private chat... During that chat, Sharafudeen provokes Nadira and she turns angry, proving herself that she was not Nadira, rather Nadiya herself who have nosebleed when gets stressed.
The truth was Nadiya- the shooter was deep in love with Zia, though he had affection only towards her identical sister Nadira- the dancer. Ustad fixes marriage y both, without consent of Nadiya and she was provoked to anger when Nadira was boasting about Zia's love to her during mobile conversation with Nadiya. She gets angry and decided to kill Nadira, by asking her to pick up at Coimbatore. When Nadira came, Nadiya assaults her and cut her nerves to bleed to death. To appear as a rape, Nadiya used her teeth to make teeth-bites on her body and changed her dress to Nadira's. She swapped her identity as Nadira, making real Nadira into coma state.
Soon after her confession to Sharafudden, she jumped out of the moving train, killing herself, which makes the real night when Nadiya was killed.
Zia (Pritiviraj)returns and takes Nadira who is in coma state to US for advance treatment, hoping she will recover.