It was grey, slightly crumpled, without a stamp and without a return address. It lay on my desk as if someone had put it there overnight. But who? With trembling fingers, I opened the envelope. Inside was a plain sheet of paper with a few words written in neat handwriting: > Don't talk to anyone about this letter. Come today at sunset under the old oak tree at the edge of the forest. I am waiting. This is important. Anyone waiting for me? But how did this someone know who I was? And what could have been so important? I glanced out of the window. An old oak tree stood on a hill, visible from my room. There was nothing there. Still. But what if someone really does turn up? Should I go? Is it a trap? What if it's some kind of secret I need to uncover? I crumpled the letter in my hand. I had until sunset.