You walk outside and something seems just a bit wrong. The sky isn't quite the right color of blue; it should be brighter. But your brain chalks it up to the fact that you're wearing sunglasses--or maybe there's a wisp of cloud over the sun. Except there's not; there aren't any clouds around. Odd. But it's probably nothing.
Then, as you walk, you start to notice there's something strange about the shadows. But not all of the shadows. Your own shadow looks perfectly normal. The shadow of a bare tree looks... off, somehow. You can't describe what's wrong with it. Then you come to a tree with…