A source stated that Saif Ali Khan had agreed to play the lead in Sujoy Ghosh's official cinematic adaptation of the Japanese novel, The Devotion of Suspect X.

Saif portrays a mathematical professor, who helps his neighbor who is accused of murdering her husband. The two characters in the film share a tense and uncomfortable screen space.

The joint effort of the two tries to throw off the hot pursuit cop which is played by Vidyut Jamwal. Kangana Ranaut will be showcasing another versatile approach by playing the female protagonist in the film. 

For the first time, Kangana and Saif will be sharing screen space, although they paired up earlier for Reema Kagti's Mr. Chaalu but soon dropped the project due to internal issues.