When we see, e.g., the haunted attic and desperate recourse to a priest (The Exorcist), the spectral sisters in the corridor (The Shining), the unhinged séance (Drag Me To Hell), the disembodied demonic footprints (Paranormal Activity), the comatose patient who seems only to be half asleep (Patrick), the body of a hypnotised man used as a portal by the dead (Two Evil Eyes), and the photographs exhibiting an eerie clairvoyant power (The Grudge, Shutter), Leigh and Whannell are not merely 'paying homage to as many films as they can', but throwing us apparent interpretative breadcrumbs that lead viewers - especially, but not exclusively, genre savvy viewers - in so many different and conflicting directions (how exactly do you get from The Exorcist to Patrick to Shutter?) that all this hyper-allusiveness conjures up its own kind of uncanny.