The house with a red door

Elaine is an internationally known architect who is said to be able to do anything. The woman is employed by an anonymous owner who pays her a considerable amount of money in advance to build a house.
The rules imposed by the anonymous person are the following:
1) The built house must be exactly like the apartment that the anonymous person has;
2) Throughout the project, Elaine must be very attentive to details, so she will move into that apartment;
3) DO NOT OPEN THE RED DOOR NO MATTER WHAT.

Easy enough, right?
But what will Elaine do when the pills stop working and she realizes that her nightmares are actually coming true in a very strange way?