Principle: A contract without consideration is void. When at the desire of one party the other party does something, the consideration is said to flow from the latter to the former.
Facts: A's house was on fire and a child was trapped inside the house. Everyone was shouting for help. A brave onlooker, hearing the shrieks of child, went inside the house and brought him out. The father of the child promised to pay the rescuer Rs.10,000. Subsequently, he backtracked his promise. The rescuer sued the promise for the breach.