Our Children's Children

On a summer's day like any other, holes opened in the air and people walked through them into our world. They kept coming and kept coming, until they numbered in millions. They said they came from the future – they were our children's children. The holes were time tunnels, one-way passages from the future. And down them were fleeing our after-generations – escaping from an invasion of intelligent yet murderously savage aliens. The tunnels were supposedly secure and guarded; the beasts, whatever they were, couldn't get through. Or so it was claimed. But then somebody up ahead slipped up, and the beasts were abroad...