You turn to the old man who is sitting working at his desk.
'Excuse me,' you say. 'I know this is your property, but I was wondering if I could have this map. You see, it would be extremely useful to me, but I understand if you don't want to part with it. I'm afraid I can't pay you...'
The old man's face breaks into a radiant smile. 'A true-hearted adventurer at last!' he says joyfully. 'All these years, and not one adventurer asked me before taking the map!'
He goes on to explain that he had set up a test for the many adventurers who came in search of the diamond.
'I'm afraid that the map is a fake,' he sighs, and your face and heart fall. You'll just have to try your luck without the map, after all.
'I can, however, help you in other ways,' the old man continues. He hands you a large leather moneybag. 'Here are thirty gold pieces. There are several shops along the way where you can buy supplies.' You tie the bag onto your belt, thanking him as you do so - you had no money of your own.
'And allow me to give you a small piece of advice. Never trust things by their appearances, down here. There are lots of evil beings that love to trick unwary adventurers. When you go back out to the corridor, ignore the other door. Inside lives a troll that has never been defeated in battle. He jealously guards two chests - one containing armour, the other weapons. They are enchanted, but I warn you - no one has ever left that room alive.'
You smile and thank the old man again and leave. Now you are yet again faced with the choice between the path and the door.