Wait until dawn) is a 1981 Indian Tamil-language thriller film, written and directed by K. Bhagyaraj.

One day, some goons kidnap Rajasekhar for a suitcase of money and Raja saves him by fighting them.

Rajasekhar introduces Raja to the screaming woman, his mentally ill daughter Sathya.

Unable to tolerate the loss, Kala jumps off a cliff and dies by suicide.

Guilty and mentally tormented about her sister's death, Sathya transforms into a mentally-ill patient.

Hearing the story, Raja requests Rajasekhar for a job to take care of Sathya and cure her illness.

The doctor nudges Rajasekhar to marry Sathya to a trustworthy groom, explaining sex is a method to cure her mental illness.

Raja tries to kill Sathya by pushing her off a cliff similar to the way Kala died so he can frame it as a suicide.

The twist is, in the accident, Sathya's mental illness is cured too and she is transformed into a sane woman.

The inspector deduces Raja is the culprit and explains it to Rajasekhar, who is hesitant to label his groom.

Sathya believes Raja tried to murder her and transfers Rajasekhar's property to his name for the fear of death.

Raja learns the truth about the woman who loves him teamed up with Sethupathy and double-crossed him to get all the property.