A highly impressive mansion is put on sale, and is an ‘open home’ for a Saturday. Large amounts of people visit the mansion, many being the rich and famous.
When six visitors and the real estate agent who just happen to be looking at the mansion at the same time, end up in the same room, they suddenly forget why they entered the room. One person freaks out and runs out of the room, but as they exit the room, they forgot the reason why they exited the room in the first place and go back inside. But when they go back inside they forget again why they re entered.
The seven people eventually work together to figure out that with every single room they enter, they forget the exact purpose of why they exactly entered it. This renders them trapped inside a huge mansion with an enormous amount of rooms.