Aditya (Vivek Oberoi), a young middle class boy, meets Suhani (Rani Mukerji), a medical student and falls head over heels for her. He pursues her relentlessly in the local trains of Mumbai. Suhani, brushes off Aditya's overtures, because she wants to become a successful doctor and do her parents proud. However, Aditya's persistence pays off and she finally accepts. But opposition from her parents forces the couple to part ways. The separation is unbearable and they get married in secret. Once they are married, is where the real story begins. The bliss ends and reality sets in with misunderstandings and quarrels in tow. Where do the newlyweds go from here? Will Aditya and Suhani understand the true meaning of being a "Saathiya"?