Hey Sinamika revolves around the story of Mouna, a weather scientist who falls in love with Yaazhan, a quirky and loving guy. After two years of their marriage, Mouna grows bitter to his constant complaining and talking, making her desperate to get rid of him. Soon Mouna chanced upon Malarvizhi, a couples therapist infamous for breaking up marriages, and an idea sparks Mouna. What ensues post that is a comedy, which quickly takes a turn as Mouna re-evaluates her decisions.