Caroline witnesses the agonizing death of her twin brother, when they are no more than 15 years old. Horrified, she feels that nobody should ever have to die. Then she discovers a hidden visitor to her home, who has the ability to live forever without aging at all. And this ability can be transmitted. As she gets to know the visitor, she finds that there are grisly downsides to such longevity. But events unfold, giving her little time...