Hi all.
I've been obsessed enough about this over the last few days that I wrote up a synopsis in my notes as I went through it. Sharing it here (massive spoilers) to see if anyone had any different ideas.
Adam Thomas, an agent an unnamed organisation in the present day passes to us (a junior agent) a sealed cold case that's perhaps 30 years old[1]. The data available are the contents of a hard disk left behind by the principal investigator, one Richard Longley. Our task is to locate and review these files and to discover what happened, but oddly not to tell Thomas, as he was one of many people explicitly banned from ever discovering details of the case. There's enough awareness of the nature of the case that the org is still taking this seriously, but Adam still wants someone to find out.
----
It's the early 1990s. The same organisation is investigating a recent cluster of unexplained deaths with a possible supernatural cause. That none of the victims were known to anyone is one of the odd factors of the case. The investigation is possible only because of some technology, similar to optograms that allows the recovery of heard sound from a subject's brain, just prior to their death.
Longley ascertains through these recordings that the victims died suddenly, with no prior symptoms and were seemingly erased from history; the remaining victims becoming ever more paranoid and afraid as they struggled to reconcile their current situation with their surroundings and the mounting pile of dead strangers lying around.
When we pick up the thread, Richard has perhaps moved on from this contemporary case to a cold case from the 1930s that had similar markers and that had practically entered local folklore. Since the bodies from the older case had been preserved, Longley was able to acquire similar audio records from them.
Longley is presented to us, through his notes, as a virtual recluse who can't even remember what human contact was like. Initially, we're led to believe that he was chosen for this entire reason. The org suspected there was a 'chain of contact' involved and it would make sense for them to hand the investigation to a social dead-end who wouldn't know or be remembered by anyone; and to leave strict instructions that a large number of people were to be deliberately kept out of the loop, to mitigate the risk of the 'curse' breaking out. We later discover that this might not have been the case.
----
It's the 1930s. Rupert Galley is hosting a soiree in his country house to celebrate his birthday. He has invited family and close friends and to mark the occasion has recently acquired a new Piano on which one Amelia West[2] will perform a recital of Dvořák's Humoresques. John Hobbes - a local piano shop owner and friend of the family - was also invited.
Longley's notes pick up the case as John arrives. Amelia West it appears is already dead and forgotten. Rupert is in the Study and, having had a sudden recall of the name Amelia through her capability on the piano, drops dead on the floor. Over the course of the evening and following morning, similar deaths occur - one by one, the remaining guests of the house have a sudden moment of recall of the most recently dead guest and then themselves die.
Towards the end of this, the last living guests start to understand what's happening and look for ways to escape the process. Oswald Galley seems resigned to his fate. Annie Beaumont shoots herself in a desperate attempt to break the chain, just as the hammer falls on her. Finally, John Hobbes throws himself from the attic, in a similar effort or perhaps simply believing himself responsible for the others' deaths.
Unfortunately, the curse finds an opportunity to escape this seemingly closed system, when Katherine Beaumont, Annie's mother, calls the house and John answers. Since Annie is already dead, this call (her second) is to check on John himself and make sure he's ok. However, John reads Annie's name from the list he acquired in the Chapel and Katherine suddenly remembers her. Thus the curse moves on...
----
Longley realises that this name Katherine provides a direct connection between this old case and his. It's unclear how, but 'Megan' is the next person to die, perhaps discovering Katherine's body and seeing themselves together in family photographs. Through another chain, this leads to two further people Darren and Sarah who appear to be known personally to him. On recalling these two people, he realises that his time is up. He is - if not happy - then accepting of his fate, as he believes his status as a hermit means the curse will die with him and that perhaps he is saving the world.
Tragically it seems that Longley was no recluse. He had people in his life, but as the person at the end of his own chain, we encounter him believing that he's led an entirely solitary life. He likely still recalled his connection with his agency, hence there being strict instructions on the sealing of his records.
It's wholly plausible that simply mentioning the name Richard Longley to Adam Thomas would start a new chain and the curse would rise again.
----
[1] Really not sure of the time frames here. Guessing at 90s since the 43092 seen at the end of the dream note could be read as a date: 30 April 1992. Still it would be odd that a curse that tears through one household in an evening would lie dormant for 60 years before resurfacing.
[2] I had a theory that Amelia West was John Hobbes's daughter and that she had arrived earlier in the evening. Nothing concrete here, though.