Ravi Khanna (Amitabh Bachchan) is a middle-class travel agent living with his widowed mother (Sulochana Latkar), wheelchair-bound sister, Renu (Farida Jalal), and young brother, Billu (Alankar Joshi), and is also due to get married with his girlfriend, Neela Rajvansh (Parveen Babi), who is the only daughter of a wealthy businessman (D. K. Sapru). One fine day, Ravi's travel agency is visited by CID Inspector Khurana (Iftekhar) and Inspector Kulkarni (Jagdish Raj) for interrogation regarding the disappearance of a man, Surendra Sinha (Rehman), who was last seen visiting Ravi's travel agency and was later apparently kidnapped. A flashback shows that Surendra Sinha had come in late on a rainy night, just before closing, to pick up the tickets that had been reserved for him, when Ravi had noticed a large emerald ring on Surendra Sinha's finger as the latter had impatiently tapped the counter while Ravi looked for the ticket. After leaving the premises, there was not a single taxi to be seen by Ravi as it had been raining heavily and that is when Surendra Sinha had offered Ravi a lift in his car till the crossroads near Ravi's house. In the present, Ravi is horrified to learn from Khurana that Surendra Sinha's dead body has been just recovered from a gutter, and it is evident that he was murdered the same night he was kidnapped, which is why no one had come forward to claim the initial ransom demand.

Despite Khurana's reassurance that it is quite a routine matter, Ravi is nervous and believes himself to be having an alibi for Khurana and Kulkarni taking a keen interest in him as he is the last known person to have seen Surendra Sinha. He seeks legal advice from his childhood lawyer friend, Advocate Rane (Shiv Kumar), for being a simple man with a family to be taken care of and wanting to do nothing with the police and the courts. However, the stress seems to be triggering severe intense headaches and Ravi ends up at the place of Dr. Shah (Sajjan), where he explains that he has had minor headaches earlier which he had ignored, but the pain has now intensified these past few days, and the headaches last for a couple of minutes each time. After being sent by Dr. Shah for a brain X-Ray, the shocking diagnosis is far more serious than tension as Ravi has a brain tumour that needs to be removed and if not, will cause his death in six months, while there is no guarantee that he will not be blind or even paraplegic as the outcome of the brain surgery. Ravi is aghast as he is the sole provider to his family and cannot contemplate a life where he becomes a burden on them, so he leaves without making a decision when the choices are death and a life worse than death. Ravi returns home, deep in thought, and his family's affection and their implicit trust in his ability to take care of them only serve to increase his conflict.

The next morning, at work, Ravi receives the interesting news of Surendra Sinha's grieving younger brother, Narendra Sinha (Satyen Kappu), having declared a handsome reward of ₹5 lakh for any information about his brother's killer. In an effort to better his family's financial conditions after him, Ravi anonymously telephones Khurana at the police station and poses as an informer about Surendra Sinha's murder, in a scheme to frame "himself" as the murderer and collect the reward money for his family, believing that he has nothing to lose and is going to die in six months nevertheless. Surendra Sinha's brother, Narendra Sinha, is ready to pay out the reward after learning about the anonymous telephone call from Khurana, who also tells him that money has to be paid to a lawyer whom the "informer" suggests, while a sealed envelope will be deposited with the same lawyer. Once the money is paid, the "informer" will inform the police over a telephone call who the killer is, and will provide the evidence as well. Narendra Sinha is willing to go through with the proposal. Now that his proposal has been accepted, Ravi meticulously sets the stage, even leaving sealed instructions and a cover letter with Rane, who is rather bewildered at the cloak-and-dagger stuff, until Khurana telephones at his office to confirm that the money mentioned in the covering letter will be entrusted to him.

Acting upon the received information, Khurana and Kulkarni recover the evidence that Ravi has created against himself and it is sent to the laboratory for fingerprint testing. Soon, Ravi is arrested by Kulkarni for the murder of Surendra Sinha and is sentenced to death for the crime by the Supreme Court of India, much to the consternation of his family, and that of Neela and her father. While Neela and Ravi's mother try to make some sense of Ravi's confession, also approach Narendra Sinha to beg for clemency, Ravi's another intense headache in prison results in him being rushed to the government hospital by Khurana and Kulkarni, where, serendipitously, it is Dr. Shah who examines him. Knowing Ravi's medical history, Dr. Shah wastes no time in getting him into the operation theatre, and the brain surgery is miraculously successful with no side-effects, but Dr. Shah is shattered to learn from Khurana and Kulkarni that he saved the patient on the operating table only to see him hung for murder. Well-aware of having condemned himself to be hung for a murder he did not commit, Ravi, during a permitted meeting with Neela and Rane at the hospital, asks Rane if he could appeal and tell the truth in the court as the sealed envelope he left anonymously in Rane's care will confirm his story after all. However, Rane's response tells Ravi that he is his friend as well as his lawyer, so the court would not believe anything he says, and that the only way for Ravi to escape the consequences of his ill-advised actions is to now find the real murderer of Surendra Sinha.

In an attempt to save himself from going to the gallows, Ravi succeeds in escaping from the hospital in search of the real killer and is aided by Neela in his pursuit. As part of his mission, Ravi investigates the significant ring of Surendra Sinha that could lead back to the killer and experiences the arrival of Michael D'Souza (Pran), a kind-hearted and happy-go-lucky small-time thief, from his own logical procedural thinking. After learning of Ravi's plight, Michael pledges to help him capture the real culprit as he is the sole witness to Surendra Sinha's murder. On the fateful rainy night, Michael had threatened the driver of a car at gunpoint and had grabbed the same costly ring from him, unmindful of the fact that it belonged to the already dead Surendra Sinha on the backseat. Despite Michael's endeavour to identify the murderer, his friend and accomplice, Prakash (Mac Mohan), a black market dealer, advises Michael to sell Ravi out to Narendra Sinha as Surendra Sinha's murderer in exchange of the reward money. Michael takes Prakash's advice and meets with Narendra Sinha at his mansion to strike the deal, where he is, however, shocked to identify Narendra Sinha as the driver of the car, whom he had threatened at gunpoint and robbed Surendra Sinha's ring from. Realising that the killer of Surendra Sinha is none other than his own brother, Narendra Sinha, Michael claims to be knowing the truth of his crime, and that he faked Surendra Sinha's kidnapping and ransom and announced the reward in front of the police to cover up his misdeeds, and sets up the meeting point of an abandoned, ramshackle wooden cottage by the riverside in the hills of Maharashtra to settle the issue.

After Michael's departure from the mansion, Narendra Sinha recalls that Surendra Sinha's wife, Mona (Ashoo), had an extramarital affair with him, which Surendra Sinha discovered on the rainy night and banished Narendra Sinha from his mansion, provoking an offended Narendra Sinha to immediately retaliate by destroying glass bottles on Surendra Sinha's head, killing him instantly due to head injuries. At the meeting point, Ravi and Neela arrive to learn the identity of the murderer, but are horrified to witness Narendra Sinha shooting Michael in the stomach fatally. Following the revelation of Narendra Sinha's crime, Ravi immediately leaves Neela to hold the fort and drives desperately to bring a doctor back in time, while a grievously injured and slowly dying Michael struggles to hold Narendra Sinha at gunpoint. On his way back, Ravi also leads Kulkarni and the police to the scene and meets with Narendra Sinha in a clash. Elsewhere, Michael gives Kulkarni and the police his testimony regarding Ravi's innocence and Narendra Sinha's crime and then breathes his last in Ravi's arms. As a result, Narendra Sinha is arrested and charged for his crimes, while Ravi is cleared of all charges and is reunited with his family.

• Amitabh Bachchan as Ravi Khanna
• Parveen Babi as Neela Rajvansh
• Pran as Michael D'Souza
• Farida Jalal as Renu Khanna (Ravi's sister)
• Sulochana Latkar as Mrs. Khanna (Ravi's mother)
• Satyen Kappu as Narendra Sinha
• D. K. Sapru as Mr. Rajvansh (Neela's father)
• Alankar Joshi as Billu Khanna (Ravi's younger brother)
• Rehman as Surendra Sinha
• Mac Mohan as Prakash (Michael's friend)
• Ashoo as Mona Sinha (Surendra Sinha's widow)
• Sajjan as Dr. Shah (Ravi's doctor)
• Madan Puri as Mahipat Rai (Ravi's one-time accquaintance)
• Iftekhar as CID Inspector Khurana
• Jagdish Raj as Inspector Kulkarni (Khurana's assistant)
• Shiv Kumar as Advocate Rane (Ravi's lawyer friend)
• Sudhir as Sharma (Ravi's colleague)
• K. N. Singh as Prosecuting Attorney
• Murad as Supreme Court Judge
• Lalita Kumari as Sulakshana Rai (Mahipat Rai's wife)

23rd Filmfare Awards:^[3]

Nominated

• Best Supporting Actor – Pran
• Best Supporting Actress – Farida Jalal

• Majboor at IMDb