Ek Din.. Achanak is a 2011 Hindi-language Drama Thriller film written by Shilpi Dasgupta, S. Manasvi, Ramapada Chowdhury and Mrinal Sen. The movie is directed by Rajeev Virani and Mrinal Sen and produced by Rohit Roy and Manasi Joshi Roy. A killer tells a woman on her 10th wedding anniversary that her husband has hired him to kill her. Ek din.. achanak features Shriram Lagoo in the title role along with an ensemble cast including Shabana Azmi, Anil Chatterjee, Aparna Sen, Roopa Ganguly, Mohan Kapoor and Sudipto Chattopadhyay. The music was composed by Jyotishka Dasgupta. Cinematography was done by K. K. Mahajan. The film has a running time of 105 minutes. It was released on 1st January 2011.

A killer tells a woman on her 10th wedding anniversary that her husband has hired him to kill her.