Lalith is a chief Clarke of a Government Department. He falls in love with Nilanthi, a newly recruited typist. But Nilanthi is attracted to another handsome young Clarke in the same department named Sagara. Lalith detests this. He starts to suspect each and every act of Sagara and Nilanthi. ‘Dahasak Sithivili’ is based on Lalith’s efforts to prevent himself from getting carried away by these endless suspicions.