In The Visit, a mother is going to leave her children for a week on a farm with her grandparents. The farm is in a very remote place, but the truth is that the children should not pass anything to them, because they are going to be with their grandparents, and we know that if someone takes good care of the children, these are their grandparents.
As the days go by the children discover something terrible. Apparently his grandparents are involved in a very murky matter, those you do not want anyone to know. That puts them in danger immediately.
What has happened is of such a magnitude that the grandparents are ready to do anything if it is not known. Children are not fools have realized that their grandparents know very well what happens.
Therefore, their hopes of leaving the farm alive are lower as the days pass. If her mother does not return soon she may not see them alive again.