There are many horrors that can freeze the blood of their victims by turning their gaze upon them. Fewer can paralyse someone with the merest knowledge of their presence.
It starts with three unhurried but insistent knocks on the front door in the stillest, most quiet dark of the night. The first wakes you in your bed, the second cuts through the hazy confusion of sleep, and the third impresses upon you that this is not some incidental noise: Someone is at the door, in the middle of the night, and they are there for you. At this point there are two choices; either answer the door, or ignore it and hope that whoever is there simply goes away. The volume of the silence that follows makes up your mind. If there was an emergency (and why else would someone come calling, unbidden, in the middle of the night) they would keep knocking.
Three minutes later, exactly three minutes later, the knocks repeat. Knock. Knock. Knock. Whoever beckons, whoever begs entry, is patient and measured. There is no mistaking this second tattoo of knocks for an accident, for someone having come to the wrong house and - in realising that the magnitude of their error is compounded by the deeply unsociable hour - skulking away in furtive embarrassment. Now the silence is oppressive, it waits on your response. It demands a response. If you hold firm in your inaction you will have another three minutes - exactly three minutes - before the knocks repeat again for a third and final time. At least for tonight.
Not privy to this information, you get out of bed and head for the front door. The adrenaline of the rude awakening and your indignation override caution and you open it widely, ready to confront whoever has chosen disturb your sleep. There is no-one there. Hand still resting on the door, blocking the entry, you lean out slightly to see if you can see someone walking (or running) away. There’s no one, no sign that there has been anyone there at all. You close the door and stand in the darkness for a few minutes, ready to yank the door open if the knocking returns. It doesn’t, and you return to your bed, taking a while to settle back into sleep.
It is an hour after the last knock, exactly an hour, when you are woken again. Groggy, you recognise that the knocking is louder, but it takes you a moment to realise why. This time they are closer. They are inside the house, and they are knocking on your bedroom door. The tone and tempo of the knocks is unchanged, identical, but that makes no difference to you right now. Panicked, you scramble out of bed, grabbing something heavy to use as a weapon in case they push open the door. You are breathing heavily, but you can hear your heart thundering and your blood roaring in your ears.
You might not have the wherewithal to expect the next knocks exactly three minutes later, but you have already decided to act when they come. You rip the door open and swing wildly, almost falling when you meet no resistance. There’s no one there. You pause for the briefest fraction of a second before retreating back into your bedroom, then shove the heaviest piece of furniture you can against the door. You stand back, away from the door, with your heavy object - what did you even grab for? - at the ready. It is exactly an hour later when the knocking repeats. It is louder than ever. It is coming from behind you, coming from inside your wardrobe.
Each haunting may vary somewhat, but the patterns of a Knocking Ghost are extremely specific: There are three knocks, repeated up to three times at three-minute intervals, at each of the three stages of ingress. If the front door is not opened after the last repetition the Knocking Ghost will leave, trying again the next two nights. This persistence and its limits carry over to the bedroom door and to whichever door it finds to lurk behind inside the bedroom. If the knocking can be ignored for three days - regardless of whether it is fear or fortitude that keeps the last door closed - the spirit will move on in search of more pliant prey.
What happens to those who have answered that third and final summons? The truth is that the conclusion to an encounter with a Knocking Ghost (at least the conclusion to those encounters that are seen through to the spirit’s intended end) remains unknown; is, necessarily, unknowable. Speculation tends to favour the belief that a victim who answers that third knock is abducted, dragged bodily into whatever spectral realm the Knocking Ghost beckons from, and swallowed up with nary a trace and without a hope of respite or reprieve. Certainly, there are no documented examples of anyone returning - or being found - once they have chosen a path more foolish than it is even arguably brave.
If someone is taken on the same night that they are first visited then, barring some hastily scrawled note or - in more recent cases - a frenzied phone call begging for aid or assistance, there is unlikely to be any evidence that their disappearance could be connected to the presence of a Knocking Ghost. Often, the only element that differentiates such potential instances from occasions where someone has run away or - perhaps somehow more ghoulishly - been abducted by a more mundane assailant, is that they are taken from within a locked room; sometimes even one that has had the doors and windows barred and barricaded in response to the earlier stages of the haunting.
Most of what is known about Knocking Ghosts is from those who have recounted their experiences to others. This typically occurs after a first visitation, in which (anecdotally at least) it seems that most people go so far as to answer both their front door and then the door of their bedroom before some pre-rational survival instinct keeps them paralysed in fear long enough for the sun to rise and for the danger to pass. In such cases they sometimes convince themselves that the experience was a dream; an alluring, if misleading, comfort that only increases the peril they are facing. This rationalisation of their inexplicable experience is less readily available to those who, quite wisely it turns out, instead run screaming into the night.
Neither response will bring the haunting to a conclusion; a Knocking Ghost will make three attempts to ensnare their chosen victim before moving on, but those who reframe and recount the experience as a dream are actually putting themselves in greater danger. The fools’ consensus known as “common knowledge” underestimates the threat of dreams, at least to those of a more or less even keel, as both slight and fleeting. When the Knocking Ghost returns then, someone under this misapprehension might weigh the risks of answering its summons more lightly, choosing the narrative satisfaction of confronting the progressive intrusions rather than giving in to a fear more justified than they can know.
The pattern of threes that presents throughout this phenomenon is the cause of much conjecture. As is often the case where numerology is expected to fill in for genuine understanding, little meaningful or even tangible insight has been gathered through such lines of inquiry. In fact, the most useful observations have been in eliminating the more unlikely and over-reaching of possibilities: The presence of threes does not, for instance, appear to meaningfully extend into the addresses or telephone numbers of the houses that a Knocking Ghost is believed to have visited (nor are third children - either overall or as represented by third sons or daughters - apparently any more likely to be taken).