First Lines Contest... Tension

The smell of death drifted from the woods.

Simple, but creepy. Note the combination of the foreboding 'smell of death' with the gentle 'drifted from the woods.'

A long, hairy leg poked through the hole in Ida’s window screen.

The mind goes immediately to 'enormous spider,' something that's definitely icky. But then we get 'poked' instead of a creepier word, and 'Ida' rather than a more normal name. You can tell this is going to be creepy and silly.