Ram Khanna is a wealthy industrialist with a trusting soul, Jeetendra who plays him. Unknown to him, his elder brother Murli Manohar Khanna Shakti Kapoor and his sister-in-law Maya Aruna Irani are after his fortune. Their greed drives them to consult an astrologer who predicts that a woman whose name starts with the letter "M" will enter his life. As fate would have it, Ram spots a dancer named Mamta Jaya Prada and is instantly smitten.
What Ram doesn't know is that Mamta is the daughter of Heerabai, Sushma Seth a prostitute. Ram learns Mamta's truth but is convinced that her roots do not make her a bad person, so he decides to marry her. Ram weds Mamta and brings her home, where she gradually realizes the true nature of Murli and Maya, and she takes control of Ram's life to thwart them. Later, Mamta gives birth to a baby boy, which makes the villains even more desperate.
One day, Ram gives Mamta a suitcase full of cash before leaving the town. Taking advantage of the situation, Murli and Maya hire a goon named Gullu Goli Gulshan Grover to kill Mamta. Gullu Goli traps Mamta when she is alone in the house, brutally kills her, and hides her body while stealing the money. However, Mamta's ghost returns, bent on revenge, and soon discovers that Murli and Maya have regained control. Everyone believes Mamta fled with the money, and Ram sinks further into sorrow and alcohol. Mamta is disheartened to see that Munna is the one who suffers most. Only Dobby the dog is able to see Mamta's presence and help in any way. Despite being a ghost, Mamta does what she can to protect her family.
When Gullu Goli resurfaces at Mamta's house, she learns the full truth about Murli and Maya's evil scheme. Gullu Goli's presence forces Dobby to act as Munna's guardian; he breaks free from confinement and saves Munna. Dobby then informs Ram of Mamta's truth. Murli pressures Ram to travel to Pune with Mona, Sahila Chaddha. Ram agrees and leaves with Mona.
Murli's plan to starve Munna for twelve hours intensifies as he tries to tighten his grip on the family. Mamta's ghost longs to touch him but cannot. As Munna cries of hunger, Mamta goes to the Mandir, where she is blessed with the power to touch everything and saves Munna. Murli and Maya realize Mamta's ghost is present. With the help of a Kaapalik, they trap Mamta. They spill their beans in front of Ram and Mona. Mona reveals that she is an undercover cop investigating the case, and that Ram had been playing along as part of the ruse. An enraged Ram attacks Murli, but the villains take him, Mona and Munna as prisoners and force him to sign over his property.
Here, Mamta is powerless to escape the trap, watching the drama unfold. She convinces the Kapalik of the truth, and the spell breaks, freeing her and giving her the power to avenge the wrongs. The would-be killers hurry to finish Ram, Mona, and Munna, but Mamta arrives to stop them. Ram, now able to see Mamta, proclaims his love. Mamta tells him she knows everything and asks him to take care of Munna. With her mission accomplished, Mamta's soul is finally set free and she vanishes.
