Chaska is based on Prem Jullundry’s hit play Halwa Suji Da Chaska Duji Da. Divorce expert lawyer Raghbir Singh (S. Raghbir Singh) is a tenant of sex-specialist Dr. V. Kumar (Surinder Sharma) and they live together in the same house. Mini (Damyanti Puri) is the lawyer’s wife and Neera (Rachna Sawhney) is Dr. Kumar’s wife.
The doctor is a rich man, possessing all the qualities of an ideal human being whereas the lawyer is just the opposite of him. His hobby is to instigate rich ladies, turn them against their husbands, get them divorced and keep them with him till he uses all their money, after which he searches for another victim. Sohna (Mahesh), the lawyer’s servant and Lachchi(Darshna), the doctor’s maidservant are having a love affair and their conversations often expose their employers’ secrets. Mini, who is often unwell, is treated by Dr. Kumar.
The lawyer starts eyeing the young, rich and beautiful wife of the doctor, in the hope of getting the house(presuming the house to be in Neera’s name) if he can marry Neera. Feigning to dislike Mini and prefer Neera, he starts instigating Neera to demand a divorce from her husband.
Mrs. Gulab (Ritu Kamal), a friend and agent of the lawyer, keeps breaking up the homes of rich ladies, persuading them to get a divorce through the lawyer. In this connection, she sends one of her distant rich cousins, Mrs Rani to the lawyer and as usual, he tries his usual tricks with her. Mini tries her best to save Neera and Rani from the clutches of her lawyer husband but neither of them listens to her. The lawyer’s cunning plans result in a split and divorce between Neera and the doctor, and himself and Mini. Mini goes to the doctor while Neera comes to the lawyer.
However, the lawyer’s dreams are shattered when the house, instead of being transferred on Neera’s name, is being transferred on Mini’s name by the doctor! He feels disgusted, starts quarrels with Neera and wants Mini to return to him, but Mini pays no attention to him. The frequent disputes between Neera and the lawyer force Neera to leave him. Rani’s patch-up with her husband causes another blow to the lawyer and on top of it the fact that Mrs Gulab also plans to take revenge and teach him a lesson.
Seeing darkness all around him, the lawyer seeks the shelter of a Saint (Chaman Puri), whose teachings open his eyes and the same Raghbir Singh chooses to repent by doing good deeds and service to others.