Words That Kill

Why, is all I think as I watch my best friend die before me. What is my word is all I think that night. You see everyone has a word that if said within ear shot of them that person will drop dead. Only problem know one knows what their word or anybody else's word is. However, the next week I bought a house, and when cleaning out the attic, I came across boxes of books. As I was going through them I found some books I didn't know, so I started to look through them. That's when I came across a book that had billions of names appearing and disappearing, all with words next to them. I realized that those words were the ones that could kill them.