Naanal was a play written by
K. Balachander and inspired by the film
The Desperate Hours (1955). After the release of
Neerkumizhi (1965), Balachander decided to adapt
The Desperate Hours as the story for his next play after being impressed by the plot.
Naanal was later adapted by him into a film with the same name after the producer Velumani felt it had potential.
Naanal marked the feature film debut of
Typist Gopu. When the film was submitted to the
censor board for certification, an official raised objection against the film's concept, believing it may influence criminals in real life to take revenge in a similar manner and instructed Balachander to change the story and film it again. Balachander, who was shocked by this decision as the film was nearing its release, made changes to the film like redubbing lines of "Judge" and replacing it with "Durai" while also shooting a flashback scene to show the reason for the criminals' anger against the film's protagonist in one day and added it in the film. After making these changes, the certification was given. == Soundtrack ==