You slowly regain consciousness. You have a headache and you are dizzy. Then you remember...: the dentist invited you for your six-monthly check-up. He had found a tooth that he thought needed to be removed to prevent worse. He anesthetized you with laughing gas so you wouldn't have any pain when pulling...

You look around and realize that you are back in the waiting room, together with a number of other patients who are also slowly recovering. Then you see that the waiting room doors can only be opened from the other side.

You can also look in the dentist's office. There you will see a heavy metal door with a combination lock. Suddenly the phone rings. You answer and hear: “Listen carefully. There isn't much time. I am the secretary of Dr. Sienski. I've watched experiments long enough. He experiments with X-rays on patients. At first everything seemed to be going well. But then some people lost their teeth and hair and became ill. We haven't seen some of them in a while...

Maybe they are dead. I don't dare go to the police myself, because Dr. Siènski works there and he will recognize me. But I can help you escape and find evidence before he starts his experiments today. First you have to open his filing cabinet. He changes the code of the combination lock every day. That code has something to do with the order of the patients that day. That's all I know. You will certainly find evidence of Dr.'s shady dealings in that closet. Siènski, just like the access code to his 'special' treatment room.

He will return in an hour and will fill the waiting room with N2O – laughing gas. To prevent this, you must turn off the main gas tap in his 'special' treatment room. If you succeed, you can overpower him when he enters. I have to hang up now and shut off the phone. Good luck!"