When A agrees to sell his car to B for one lakh rupees, a valid contract is formed between the parties. However, before the delivery of the car, if the subject matter of the contract—the car—gets completely destroyed due to an unforeseen event such as an accident, the contract cannot be fulfilled.
In this situation, the contract is discharged by the Doctrine of Frustration. According to this doctrine, if after the formation of a contract, an unforeseen event occurs which makes the performance of the contract impossible or unlawful, the contract is automatically terminated.
The destruction of the car is an event beyond the control of either party, which renders the performance of the contract impossible. Neither party is held liable for non-performance because the foundational basis of the contract no longer exists.
This doctrine is codified in Section 56 of the Indian Contract Act, 1872, which states that a contract to do an act impossible in itself is void.
Conclusion:
The contract between A and B is discharged by the Doctrine of Frustration due to the complete destruction of the subject matter before delivery.