Narration: Murdering his grandfather in 1905 meant that Elmer's mother didn't exist to meet his father in 1925. Which made certain that Elmer himself was never born. Elmer killed his grandfather, so his mother was never born. But if his mother was never born, Elmer no longer exists. But if Elmer no longer exists, how could he possibly kill his grandfather? And around and around we go. Elmer has created a paradox, the grandfather paradox. The most pernicious problem in The Commission Handbook of Paradox Protocols. This story is not true. But if it were, Elmer would have placed time, space, and every living thing in grave peril. Don't be an Elmer! We've been lucky so far. With your help, constant vigilance, and a little strategic violence, the Commission will make certain nothing like this ever happens. Or God help us all.