A highly regarded architect leaves a prestigious firm to start his own practice. He is in demand, but struggles with his workload vs. his deep-rooted feelings of inadequacy.
Having won several design awards, he is up for yet another, and his former architectural firm tries to persuade him to return to their practice, but he decides to continue on his own.
Meanwhile, his marriage is falling apart due to his over-commitment to his career, and he begins to hallucinate that he is being followed by someone. His escalating alcoholism doesn't help these paranoid delusions...
He is approached by a man (an identical twin) claiming that he is the main character's "double"...an alter-ego, and that they are the same person. The main character has several "deja vu" episodes that his "doppleganger" warns him about, as if two separate lives are almost overlapping. However, he refuses to believe in this mysterious stranger that dogs him wherever he goes.
Eventually, disaster does happen...a building that the main character designed collapses, killing people and leaving him with guilt and self-doubt.
His tormentor arrives and a self-destructive assault ensues and his "double" continues to torment him.