It by Stephen King

To the children, the town was their whole world. To the adults, knowing better, Derry, Maine, was just their home town: familiar,well-ordered, a good place to live. It was the children who saw - and felt - what made Derry so horribly different. In the storm drains, in the sewers, It lurked, taking on the shape of every nightmare, each person's deepest dread. Sometimes It reached up seizing, tearing, killing...