The train
No.20 Madras Mail to
Madras starts from
Trivandrum Central railway station. R. K. Nair, a
Kollam-based businessman takes the first class coach to Madras with his wife Geetha and daughter Devi from
Kollam Junction. Tony Kurishingal, along with his friends Hitchcock Kanjikkuzhi and Kumbalam Hari boards the same coach from
Kottayam. Tony is the son of a wealthy businessman, Kurishinkal Kariyachan, Kanjikuzhi is a
detective novelist and Hari is a young politician. Three of them are going to Madras to see a test
cricket match, a
cabaret, and to make attempts to make Kanjikuzhi's novel
Vaarikkuzhiyile Kolapathakam a movie. All three are drunkards.From
Ernakulam Town station, another passenger Sunil boards the train at the last moment. After seeing Devi, Tony and friends make several attempts in getting a seat for Tony in the same coach of Devi, with the help of ticket inspector Nadar, but with little success. While doing so, Tony gets into heated arguments with Nair and Sunil, who shares the same coach. Film actor
Mammootty himself boards the train from
Thrissur and gets into the same coach. Nadar leaves the train at
Palakkad after giving company with Tony and gang and the new TTE Chokalingam / Choki assumes duty. Tony and his friends visit Mammootty and become friends with him. Meanwhile, Tony tries to flirt with Devi while she returns from the restroom, which causes Tony to land in trouble with Nair, but on Mammootty's intervention the matter is settled. In the morning, as the train reaches
Madras, Devi is found murdered in the toilet. Suspicion lands on Tony and friends and they run away from the spot in fear. The investigation is carried out by police officer DySP Murthy who learns from Chokalingam that Mammootty had taken photos of Tony and friends while in the train. He gets the photo from him and are publicly displayed. Mammootty helps Tony and friends to return to Kerala secretly as he believes they are innocent. Back in Kerala, they are confronted by Sunil. Sunil sneaks upon Tony holding a
switchblade at the lake where Tony, Hari and Kanjikkuzhi were bathing. Sunil attempts to murder Tony, Hari and Kanjikkuzhi, thinking they murdered Devi. Tony defeats and subdue Sunil in the fight that ensued. Tony orders Sunil to spill information about Devi's killer. Sunil was actually the lover of Devi and both had planned to elope from the train at
Erode, but failed as Sunil could not get out off the train in time during the halt. Devi, with the help of the station master takes a taxi to the next station,
Salem, and get back to train. Sunil makes amends with Tony, Hari and Kanjikkuzhi and becomes their new friend. Also, from Sunil, they learn about Sr. Gloria, who tells that Devi gave her a
diary before leaving for Madras. After acquiring the diary from the convent, they come to know that Nair is not Devi's father, but only a stepfather and that he killed her father in her childhood. On learning that Nair might be the murderer, Tony calls Nair by phone impersonating Mammootty's voice and says that he has got the diary and
blackmails him to give ₹20 lakh in return for the diary. Tony informs Mammootty and convinces him to proceed with the play. Mammootty and Nair meets and agree to fix the deal on the same train on a Wednesday. Mammootty boards the train at
Palakkad on which Nair has already booked an entire bogie. He informs that the diary is not present with him and would hand it over at Salem when Tony joins the train. Nair leaves the train at
Erode Junction railway station and goes to Salem station via taxi to find Tony, but Tony and Sunil enter the train in between, they along with Mammootty overpower Nair's henchmen. Meanwhile, Nair reenters the train at Salem Jn. and finds that Tony has already entered. Tony and Mammootty attack Nair and make him confess the truth. Nair reveals that he killed Devi after she caught up the train at Salem, fearing that Devi would inform the police about her father's murder. The next morning, when the train arrives Madras, DySP Murthy, who had already been informed of everything by Hari and Kanjikkuzhi, arrests Nair and his goons. Tony, Hari, and Kanjikkuzhi has proved their innocence. On another day, while boarding the No.19
Trivandrum Mail to return home, they find Mammootty again in the same train, who tries to leave the train after seeing them, but only to be stopped by Tony and friends who promises a happy and safe journey back home. == Cast ==