This riddle is my take on the Monty Hall problem. If you know the original version, this one should be very easy for you.

You are watching the TV series “Lets Make a Deal”. You are very excited as you know that your friend Heidi is participating today. You watch attentively throughout the show, only to find out that it ends without Heidi ever appearing in it.

You call Heidi, several times during the following day, but you keep getting her answering machine. Maybe something happened to her?

You recall the Rules of the Show:

The host presents each candidate with three closed doors. Behind one of the doors hides a big prize, behind the other two there is an empty bucket. The candidate chooses one of the doors (this choice is random as they have no information whatsoever on the location of the prize). Then the host opens one of the other doors behind which there is no prize. Then the candidate is given the option to remain with his initial choice or to switch doors and choose the other closed door. Then the remaining doors are opened, and the candidate is awarded whatever is behind the door they finally chose. The goal of the candidate is (obviously) to choose the door with the prize.

Pondering about the rules, you develop the following theory:

Maybe the host does not know in advance which of the doors contains the prize. In that case, if the host happens to choose to reveal the door with the prize (thus ruining the show) the candidate is killed (finally, some proper riddle scenario) and the scene is cut-out during the editing of the show.

Maybe that is what happened to Heidi?

Assuming that you have a lot of episodes (as many as you need), how can your theory be ruled out or strengthened?