13 Steps Down (2012)

Mix Cellini is a young man with a disturbed past. He rents the top floor of a dilapidated Notting Hill residence in which a lonely spinster in her mid-70s lives. Two obsessions in Mix's life are supermodel Nerissa Nash, who he adores and stalks, and infamous serial killer John Reginald Christie. Mix treads a fine line between reality and fantasy, and his obsessions collide when he unleashes long pent-up violence after his part-time girlfriend criticises his beloved Nerissa.