"Button, Button", Richard Matheson
A package arrives at Norma and Arthur Steward's house with a gadget inside with a button on it. Shortly after a man arrives and announces to the couple that if they push the button they will kill someone in the world, and receive $50, 000 in exchange. Norma is intrigued by this, insisting that they are part of an experiment, and nothing will happen if they push the button. Except maybe they would get paid and could do the many things she was longing for. Arthur is repulsed by the idea and by his wife. This is a very well -written story although you will probably guess the ending. This was, of course, on the Twilight Zone. You can watch it on you tube. It was also the plot of the 2009 movie THE BOX.
