Film's music was by Laxmikant-Pyarelal, giving successful numbers like, 'Om Shanti Om' and 'Dard-E-Dil', and who went on to win Filmfare Best Music Director Award for this film,the lyricist received two Filmfare nominations for these two hits.
Ravi Verma wins a legal battle against Sir Judah, his dead father's business partner. Shantaprasad Verma, Ravi's dead father, was a rich man in Coonoor, whose property was unjustly usurped by Sir Judah after his death. Ravi gives the good news to his mother without realizing that Judah has already set contrary plans in action. Ravi has fallen in love with Kamini, a gold-digger working covertly for Judah. Here, Ravi tells his mother that he is going to get married & coming back to get her blessings for him & Kamini. On their way to Coonoor, Kamini throws Ravi off the cliff near a small temple of Goddess Kali.Two decades later, Monty, an orphan raised by G.G.Oberoi, is a twenty-one-year-old singer fond of a tune Ravi liked, which activates some of Ravi's memories subconsciously present in Monty.
Monty soon falls in love with a girl identified later as Tina. While singing a song in his show Monty suffers a nervous breakdown, & is advised a vacation in some remote place. He chooses Ooty (near Coonoor), partly because Tina lives there. There, his inherited memories become intense when he sees all the locations of these memories. Tina tells him that she was brought up by her Rani Sahiba at behest of her uncle Kabira. In truth, Kabira was sentenced to life imprisonment and is about to be released, whereafter Monty wins his permission to court Tina, but learns that Rani Sahiba is Kamini. Kabira later reveals to Monty that Tina's father learnt some deadly secret about the Kali temple, Kamini and Ravi Verma, for which Kamini's brother killed him. In retaliation, Kabira killed Kamini's brother & blackmailed her to raise Tina with proper education, by pretending to know the secret. Monty has also learnt previously that Ravi's mother & his sister were ousted unjustly from their house by Kamini & her brother. He tells the whole story to Kabira, who offers to find Ravi's estranged family, with whom Monty is united. Realizing that Kamini is a puppet of Sir Judah, Monty gradually convinces that Ravi's ghost seeks revenge. Slowly, a rift is caused between her & Sir Judah. Finally, in the local school opened by the Verma family, an inauguration of a hall in the memory of Ravi is planned by the school. Kamini Devi has to do the inauguration. Monty & Tina perform at the function, where they dramatise Ravi's story.
Kamini is horrified to see Ravi's mother & sister, and flees. When Monty confronts her, Kamini confesses to Ravi's murder, which the police record; whereupon Judah captures Ravi's relatives and agrees to release Tina in exchange for Kamini. Just as the exchange is about to take place, Tina attacks Kamini. In the melêe, Kabira & Monty gain an upper hand. Judah tries to burn down Monty's family, but Monty saves them and kills him in a fire. Kamini escapes through the jeep. Pursued by Monty, she attacks him at the temple, but falls to her own death. In the end, Monty marries Tina.Direction – Subhash Ghai
Screenplay – Sachin Bhowmick
Dialogue – Dr. Rahi Masoom Reza
Production – Akhtar Farooqui, Jagjit Khurana
Editing – Waman Bhonsle, Gurudutt Shirali
Cinematography – Kamalakar Rao
Direction Assistant – Ashok Ghai, Kuku Khanna
Art Direction – Sudhendu Roy
Costume Design – Bhanu Athaiya, Bhavana Munim, Satyawan
Choreography – Suresh Bhatt
Music Direction – Laxmikant-Pyarelal
Lyrics – Anand Bakshi
Playback – Mohammed Rafi, Asha Bhosle, Kishore Kumar, Lata Mangeshkar, Manna Dey, Anuradha Paudwal
The soundtrack of the film includes tracks, composed by Laxmikant-Pyarelal, and with lyrics by Anand Bakshi, who received two Filmfare nominations for these two hits, 'Om Shanti Om' and 'Dard-E-Dil', Laxmikant-Pyarelal however won the trophy for Best Music Director of the year. With hits like, "Ek Haseena Thi " and " Om Shanti Om " by Kishore Kumar and "Dard-E-Dil" by Mohd. Rafi, the soundtrack was a trendsetter for the disco music in the Indian music industry and film's background score, especially the signature tune are still remembered as one of the most memorable ones.
The film's chart-buster song, Om Shanti Om, sung by Kishore Kumar, reached the number 2 spot on the Binaca Geetmala's annual list 1980, while another duet between Lata and Kishore, Tu Kitne Baras Ki reached number 13.
All lyrics written by Anand Bakshi; all music composed by Laxmikant-Pyarelal.
Meanwhile, the Filmfare Best Music Director Award notwithstanding, the film's music turned out to be heavily "inspired" in the later years, like the dramatic Ek Hasina Thi was taken from George Benson's As We Love, while Om Shanti Om itself came from Trinidad Calypso artist Lord Shorty's version
The story of this movie about reincarnation and revenge became the ninth highest grosser of the year, and was declared a "Semi Hit" nationwide. In a 2008 interview, film director, Subhash Ghai admitted that film was ahead of its time, and was thus panned by critics of the times, and "flopped" at the box office, it was only years later that it started being considered a classic and even remade several times over.
The film is also one of the finest films of Subhash Ghai, notable for picturisation of songs like Ek Hasina Thi on stage as well as Dard-E-Dil, and set the standard for his future films, as most of them became known for his dramatic flair, and above all their music score. However, the director Subhash Ghai admitted that Karz was partly inspired by the 1975 American film The Reincarnation of Peter Proud, mixed in with Indian beliefs on reincarnation. Karz may have also been inspired by the 1958 Hindi film Madhumati. Karz was itself remade several times: as the Kannada film Yuga Purusha (1989), the Tamil film Enakkul Oruvan (1984), and more recently the Hindi film Karzzzz (2008). Karz may have also inspired the American film Chances Are (1989).
Though the theme of reincarnation was earlier handled in Madhumati (1958), Kudrat (1981), and Mehbooba (1976), the modern twist with murder and revenge angle set in Karz was a pot-boiler; it went on to inspire several other Indian remakes, notably Yuga Purusha (1989) in Kannada, Enakkul Oruvan (1984) in Tamil, Atmabhalam (1985) in Telugu, and the most recent Hindi film Karzzzz (2008) starring Himesh Reshammiya.
The songs of the film inspired several film titles, notably Paisa Yeh Paisa (1985), Main Solah Baras Ki (1998), Ek Hasina Thi (2004), Aashiq Banaya Aapne (2005) and Om Shanti Om (2007), which was seen as light-hearted tribute to the film, as it borrowed many elements from it.1981: Filmfare Award
Best Music Director: Winner: Laxmikant-Pyarelal
Best Supporting Actress: Simi Garewal: Nominated
Best Male Playback: Kishore Kumar: "Om Shanti Om": Nominated
Best Male Playback: Mohammed Rafi: "Dard-E-Dil": Nominated
Best Lyricist: Anand Bakshi: "Om Shanti Om": Nominated
Best Lyricist: Anand Bakshi: "Dard-E-Dil": Nominated"