Oru Naal Koothu is a story connected by the theme of marriage. Several characters find themselves entangled, including Raj Kumar (played by Dinesh, who doesn't quite convince), whose colleague and lover, Kavya (Nivetha Pethuraj, noteworthy in her debut), is set to marry someone else. Despite still harboring feelings for him, she’s asked to wait because he has a family—one he admits he doesn’t love but feels responsib…