No. 20 Madras Mail (1990)

Set against the backdrop of the No. 20 train to Madras, this fast-paced thriller opens at Trivandrum Central, where R.K. Nair (M.G. Soman), a Kollam-based businessman takes the first class coupe of the train to Madras with his wife Geetha (Jayabharathi) and daughter Devi (Suchitra) from Kollam Junction. Tony Kurushingal (Mohanlal), along with his friends Hitchcock Kanjikuzhi (Manianpilla Raju) and Kumbalam Hari (Jagadish) boards the same coach from Kottayam.

Tony is the son of a wealthy businessman, Kurishinkal Kariyachan (Jagannatha Varma), Kanjikuzhi is a detective novelist and Hari is an young politician. The three of them are going to Madras for seeing a cricket match and to make attempts to make Kanjikuzhi's novel Vaazhikuzhiyile Kolapathakam into a film. All the three are heavily intoxicated and excessively under the influence of alcohol while boarding the train. After entering the train and seeing Devi, Tony and friends make several attempts in getting a seat for Tony in the same coupe of Devi with the help of TTE officer Nadar (Innocent), but everything fails.

While doing this Tony gets into heated arguments with RK Nair and Sunil (Ashokan), who has a reserved seat in the same coupe (from Ernakulam) with R.K. Nair. Actor Mammootty boards the train along the way from Thrissur railway station and gets into the same coach. Nadar leaves the train at Palakkad after giving company with Tony and gang and the new TTE Chokalingam a.k.a. Choki (Jagathy Sreekumar) enters the train.

Tony and his friends visits Mammootty in his coupe and soon become friends with him. Meanwhile Tony tries to flirt with Devi while she returns from toilet, which causes Tony to land in trouble with R.K Nair which Mammootty helps to resolve. Finally, everyone settles down for the night.

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 scene in fear. The investigation is carried out by the Police led by DySP Murthy (V.K.Sriraman) who comes to know via TTE Chokalingam that Mammootty has taken photos of the suspects while in the train. He visits Mammooty and gets the photos and asks him to not try to save them.

Tony and friends seek Mammootty's help and he helps them to return to Kerala secretly. Back in Kerala, they are confronted by Sunil, who was actually the lover of Devi. Both had actually planned to escape from the train at Erode, but failed due to Sunil's delay in getting down from another side, which was planned due to not arousing suspicions. Devi, with the help of station master had then taken a taxi to the next station (Salem) in order to catch back the train from there.

Also, from Sunil, they learn about Sr. Gloria (Sumalatha) who tells that Devi gave her diary before leaving for Madras. After acquiring the diary from the convent they come to know that R.K Nair is not Devi's father and that he is the one who killed her father in her childhood. On learning that RK Nair might be the possible murderer, Tony calls RK Nair by phone impersonating Mammootty's voice and says that he has got the diary with him and blackmails him to give Rs 20 Lakhs in return for the diary.

Tony tells this to Mammootty and convinces him to proceed with the play. Mammootty and RK Nair meets and agrees to fix the deal on the same No 20. Madras Mail on December 21. Mammootty boards the train at Palakkad on which RK Nair has already booked an entire bogie. Mammootty says that the diary is not present with him and he 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 enters the train in between and with Mammootty's help they power down RK Nair's henchmen. Meanwhile Nair renters the train at Salem Jn and finds that Tony has already entered. Mammootty and Tony attacks Nair and make him confess the truth that he killed Devi after she caught up the train at Salem.

The next morning, when the train arrives Madras, DySP Murthy arrests RK Nair who was already been informed of everything by Hari and Kanjikuzhi. On January 1 while boarding the No 19 Trivandrum Mail to return home, they find Mammootty again in the same train. Mammootty tries to leave the train in disguise only to be stopped by Tony and friends who promises a happy and safe journey back home.