"Each man measures his time; some with hope, some with joy, some with fear. But Sam Forstmann measures his allotted time by a grandfather's clock, a unique mechanism whose pendulum swings between life and death, a very special clock that keeps a special kind of time - in the Twilight Zone."
Sam believes that when a grandfather clock he has owned all his life stops, he will die. To make his granddaughter happy, he sells the clock to a neighbor. While the neighbor is away on vacation, the clock begins to wind down. When it stops, Sam's spirit begins to leave his body, but Sam realizes the spirit is just his imagination and it disappears."Clocks are made by men, God creates time. No man can prolong his allotted hours, he can only live them to the fullest - in this world or in the Twilight Zone."