With his mind transferred to another body, Number 6 wakes up in his London flat and can't convince his colleagues who he is. He takes off to Austria to find the one man who can help him, the person Number 2 wants him to find.
Number Six wakes up with a new identity. Now he's Number Twelve. Worse, Number Two asks him to impersonate someone--Number Six. But the new Number Six is more like him than he is.
Number 2 believes that Number 6 resigned because he was going to sell out. Using dream manipulation, Number 2 tries to determine which one of three possible candidates Number 6 was dealing with.