Govind (Rajesh Khanna) is a young sculptor. While vacationing near Kullu, he sees Lajjo (Indrani Mukherjee) and falls in love. Subsequently, they get married secretly in a village temple. He then has to leave for the city to further his education. Meanwhile, the girl learns that she is pregnant. On finding this, her stepmother sells her off for Rs. 500, where she is beaten. Some time later, she gives birth to a little boy named Buntu. Later, Lajjo comes to Mumbai to meet Govind, carrying her one-year-old son. She leaves a letter for him at his doorsteps, and wants to leave the child with him as well. However, she is unable to go through with it, so she takes Buntu with her. They keep wandering and feed off whatever comes their way, but soon she dies leaving her son alone.

The rest of the film is a story of the little child, wandering around the city. He goes out of the house, eating whatever he finds, including a pill, which makes him doze off. On waking up, he wanders even more and more into the city. Meanwhile, Govind, comes know all through a letter she has left behind, Aakhri Khat (Last Letter), he soon realizes his mistake and with the help of police tries to find his wife and son, though only finds his wife's body. Later, he shows the Police inspector Naik, (Manvendra Chitnis), the statue of Lajjo he has kept in his studio.

The child is then rescued by a man who is a staff member of an orphanage nearby. He escapes from that place at night. And after a long time of wandering here and there, and after the help of some people, he ultimately reaches home to find a statue of his lost mother, and a new lady, who is now his new mother.^[6]

• Rajesh Khanna - Govind
• Indrani Mukherjee - Lajjo
• Master Bunty - Buntu
• Nana Palsikar
• Manvendra Chitnis - Inspector Naik
• Mohan Choti - Moti (Servant)
• Tun Tun
• Maruti Rao
• Naqi Jehan - Wealthy young woman

Rajesh Khanna disclosed in an interview,"I consider “Aakhri Khat” a memorable film of my initial days. It was out and out a director's project and Chetan Anand, highly imaginative and sensitive director handled the film with expertise. I still clearly remember how cinematographer Jal Mistry shot the song sequence, “Ab Na Ja” on me and Indrani Mukherjee in five to six close ups also picturising the natural panorama of the Himalayas with rare aesthetics and perfection. My most challenging scene in “Aakhri Khat” was the last one where I am in a pensive mood in silence till I recognise my son, Bunty. Chetan Anand used to wake me up with late night phone calls so that my face had the ideal pathos oriented look."^[7]

The soundtrack includes the following tracks, composed by Khayyam, and with lyrics by Kaifi Azmi, also marked the debut of Bhupinder Singh as a solo playback singer.^[8]

• List of submissions to the 40th Academy Awards for Best Foreign Language Film
• List of Indian submissions for the Academy Award for Best Foreign Language Film