Knock Knock Knock

Who is knocking on Ian Frazer's door at 3.15am every night? Is it a prank? Is he hallucinating? Or is it something far worse?Ian Frazer is a lecturer commissioned to write a book about the death of a miner during the strike of 1984. He lives alone in the one remaining flat in a condemned block. Every night at exactly the same time he is awakened by someone pounding on his door. Is the visitor in some way connected to the book? Ian has to find out.