As per Section 105, of Indian Succession Act, if the legatee (person named in will as, successor of the property or, one who receives legacy in will) dies before the testator (person who makes the will regarding succession of his property), then the will or legacy cannot take effect.
However, as per Section 106 of the Act, in case of joint legatees, the legacy does not lapse and the property of the departed legatee goes to the surviving legatee, unless the testator has not provided any other instruction in will that the property of departed legatee will go to some other person.
Also, as per Section 109 of the Act, in case the legatee is a child or lineal descendent of testator, dies leaving a lineal descendent (children, grand-children, great grandchildren and so on) of him who survives the testator then, the will or bequest shall not lapse and will take effect as the death of the legatee had happened immediately after the death of the testator, unless a contrary intention appears by the Will.
So, by above statements it is clear that in case of death of sole legatee, the will cannot operate. In case of joint legatee, if the departed legatee is a child or grandchild (lineal descendent) of testator and has his own child (lineal descendent) then, the share of the departed legatee in “will” will be succeeded by his lineal descendent by the rule of general succession after the death of testator. In case joint legatee is not a lineal descendent of testator or do not have any lineal descendent of his own, then the share of departed legatee will be given to the surviving legatee.