'A door appearing from nothing is impossible. A door appearing from nothing is inexplicable.'

This is an unsettling, nightmarish thought experiment. I kept asking myself what I would do if another me walked out of a mysterious door in my basement. At first, Dr. Tamsin's doppelganger seems benign and helpful even, but things spiral out of control and I couldn't read fast enough. I struggled to get into this during the first 20%, but I couldn't put the last 80% down! This is a fantastic blend of psychological/existential horror and sci-fi thriller. 

'It is exactly like every other door in her house, entirely unremarkable, except for two things: It did not exist twelve hours ago, and it will not open.'