When I came into the room, my computer was on. It worried me since I didn't remember switching it on. I looked around – there was nobody in my room and everything was in its usual place. Suddenly I understood – the book had gone! I had left it on the table but it wasn’t there any more. I checked the window – it was closed. That meant that someone had come into the room through the door. My first impulse was to call the police but I called Jim instead. “What has happened?” Jim sounded sleepy. I explained that someone had taken the book. “Oh, no!” Jim sounded unhappy. “Have you any idea how valuable it is?” “There’s another thing I can't understand,” I interrupted Jim. “My computer’s on but I always switch it off before leaving home.” “Ok, stay at home. I’ll be at your place in half an hour,” he said and the phone went