Chennai, Oct 15 : Actor Karthi, who plays the lead in director P. S. Mithran's upcoming spy thriller, 'Sardar', has disclosed that it was director P. S. Mithran's single-line narration on how the army chose to recruit a theatre artiste and turn him into a spy that got him hooked onto the project. Speaking at the trailer launch event of the film on Friday, actor Karthi said: "When producer Lakshman made me meet director P. S. Mithran, the latter casually narrated a one-liner to me. Mithran told me that in the eighties, when the Indian government was looking to set up a team of spies, they tried to train some of those in the military to act. "However, despite a lot of effort, those in the military couldn't act. That was when the think tank thought, 'Why should we strain so much? Why should we not take a theatre actor and put him in the military?' So, a theatre artiste was recruited and a team trained him and sent him to Pakistan. "That idea itself was stunning. A theatre artiste being converted into a spy. It was interesting. On learning about this, I asked Mithran to write the script. After a couple of revisions, Mithran came back and told me that the script had taken shape but that it had changed into a double action script. Mithran said, 'This story requires double action. Otherwise, it can't be done.' So, that was how 'Sardar' began." The film, which is to hit screens on October 21, features Karthi in double action - one as a spy and another as a police officer crazy about publicity. Apart from Karthi, the film also features Chunkey Pandey, Laila, Rajisha Vijayan and Raashi Khanna among others. Music for the film has been scored by G. V. Prakash Kumar and cinematography is by George C. Williams. Editing is by Ruben and Art direction is by Kadhir. /IANS