On a dark stormy rainy night in Allahabad, Hari Shankar (Ashok Kumar) enters a mansion, he had recently purchased. The caretaker is a mali (gardener) Kumar, who narrates the tale of obsessive love, and sacrifice that took place there nearly 40 years ago. The mansion by the banks of a river had Kamini staying there. Her lover visited her every night. Unfortunately a stormy night drowned the lover in the river. Before drowning, he promised that he would meet her in another lifetime. Kamini too drowned and died.
Shankar wanders around the mahal and finds the portrait of the previous owner. He is amazed that it has uncanny resemblance to him. He wonders at reincarnation. And soon hears a haunting melody - Aayega aane wala. He follows the singer Kamini (Madhubala, 16), who dressed in white, appears and disappears. Soon Shankar's lawyer friend Srinath (Kanu Roy) arrives. He tries to make Shankar realize that there is no reincarnation and Shankar should let go of tragic lover story. But Kamini is all 'real' and Srinath has no explanation.
Srinath reminds Shankar that he is engaged to be married and must return to Kanpur, his birthplace. Srinath promises to sell the mansion. Shankar leaves for Kanpur but gets off at Naini and soon returns to the Allahabad mansion. He is the obsessive lover, who cannot give up on Kamini. Srinath's efforts to take him away from Kamini prove futile. Kamini tells Shankar that they can be together if he can kill the mali's daughter Asha and she can then possess her body. Before Shankar can kill Asha, Srinath stops the murderous try.
Shankar is soon married to his fiancée Ranjana (Vijayalaxmi). But he cannot forget Kamini and refuses to have conjugal rights. Ranjana vows she'll remain in veil till Shakar lifts it and sees her face. Ashok leaves her to return to the mansion to kill Asha and reunite with Kamini. Ranjana feeling humiliated, consumes poison but in police station puts the blame on Shankar that he poisoned her and dies after signing her confession.
Shankar reaches the mansion and calls for Asha. When he sees her, he asks her to lift her veil. Before she can do it, police comes and arrests him. In the court, he denies killing Ranjana. He cannot identify Ranjana as he had never seen her face. Finally Asha appears in the court and lifts her veil. She is Kamini! She tells the court that in the mansion she had seen the portrait of the lovers and she fell in love with the man in portrait. So, each night she dressed in white and sang the haunting melody. and one fine night Shankar came, an exact replica of the man in portrait. She fell in love with him. They were the lovers from the earlier life.
But the court gives death by hanging to Shankar for murdering his wife. Shankar tells Srinath to marry Kamini so that the curse on the lovers should get over and he can unite with Kamini in next life. On the day prior to hanging the postal department finds a letter (suicide note) of Ranjana, in which she states that she is taking her own life as Shankar has rejected her in favor of another woman. The police goes to the Chief Justice of Allahabad High Court and Shankar is pardoned. Shankar comes to Srinath's house, only to find him married to Kamini. He dies sacrificing his love.
Kamal Amrohi had created a classic tale of obsession, love, and sacrifice that still has no parallel. Mahal was also India's first reincarnation movie that catapulted Madhubala at 16 to overnight fame. And Lata Mageshkar became the singing sensation with Aayega Aane Wala. The movie took box office by storm. Music director Khemchand Prakash became immortal and lyricist Nakshab Jarchavi never lacked work.
The first Hindi reincarnation movie was probably Punar Janam (1938). Bimal Roy, Mahal's editor later made Madhumati (1958), another reincarnation tale, and it gave birth to other movies like Milan (1967), Neel Kamal (1968), Milap (1972), Mehbooba (1976), Karz (1980, 2008), Kudrat (1981), Nigahein (1989), Suryavanshi (1992), Prem Shakti (1994), Karan Arjun (1995), Prem (1995), Hameshaa (1997), Tales Of The Kama Sutra 2: Monsoon (1998), Ab Ke Baras (2002), Jaani Dushman: Ek Anokhi Kahani (2002), Paap (2003), Mr Ya Miss (2005), Om Shanti Om (2007), Quick Gun Murugan (2008), Love Story 2050 (2008), Karma: Crime Passion Reincarnation (2009), Chandni Chowk To China (2009), Makkhi (2012), Dangerous Ishq (2012), Teri Meri Kahani (2012), and Ek Paheli Leela (2015).
There have been movies and more movies on the theme of reincarnation in Hindi Cinema but none could beat or even come close to Mahal.
Watch the full movie on youtube.