No. 20 Madras Mail

A wealthy, impulsive young man who travels with his friends to Madras for entertainment and to see a cricket match. He flirts with Devi and finds himself entangled in trouble, yet his loyalty to his friends guides his actions as the mystery unfolds.

A passenger who captures Tony's attention and later becomes central to the mystery. She is connected to Sunil, carrying a diary that reveals family secrets, and her fate drives the investigation across the train journey.

A flamboyant detective novelist traveling with the group, obsessed with turning his novel into a film. His quick thinking and bravado help the friends navigate the escalating trouble and misdirections.

A young politician and member of the trio, Hari represents ambition and energy. His loyalty to friends is tested as the plot thickens, and his actions help drive the pursuit of truth.

The wife of R. K. Nair, present in the journey and part of the web of relationships surrounding Devi’s murder. She observes the unfolding events and contributes to the social dynamic on board.

A Kollam-based businessman who is Devi's stepfather and a central figure in the motive for murder. His attempts to protect his secrets propel the plot toward a dramatic confrontation.

The ticket inspector who initially helps Tony secure a seat and later provides crucial information during the investigation. He offers practical aid and serves as a grounded, helpful presence.

Devi's lover who plans to elope from the train. He becomes entangled in the drama, initially feared as a suspect, but ultimately provides key information about Devi and her past.

The TTE who interacts with the passengers and assists in managing the journey. His presence adds humor and helps move the plot through the logistical obstacles on board.

A nun who provides crucial information about Devi via her diary, helping the investigators piece together Devi's past and the motive behind the murder.

A wealthy businessman and father of Tony, whose prominence and authority influence the dynamics among the travelers and the unfolding drama.

One of the antagonistic goons aligned with the trip's misadventures, contributing to the tension and danger aboard the train.

Another member of the goon presence, amplifying the risk and roughness faced by the protagonists during the journey.

A famed film actor who boards the train and ends up helping Tony and his friends. His cameo adds a meta-cinematic layer to the narrative.