Turn down Slade Alley - narrow, dank and easy to miss, even when you're looking for it. Find the small black iron door set into the right-hand wall. No handle, no keyhole, but at your touch it swings open. Enter the sunlit garden of an old house that doesn't quite make sense; too grand for the shabby neighbourhood, too large for the space it occupies. A stranger greets you by name and invites you inside. At first, you won't want to leave. Later, you'll find that you can't. This unnerving, taut and intricately-woven tale begins in 1979 and reaches its turbulent conclusion around Hallowe'en 2015. Because every nine years, on the last Saturday of October, a 'guest' is summoned to Slade House. But why have they been chosen, by whom and for what purpose?