The Faithfuls

INNOCENT BUT ANNOYING STRANGERS ARE BEING MURDERED ONE BY ONE
Welcome to a medieval castle in the wilds of Scotland. Arriving here are contestants in the world's most popular new TV Reality show: two dozen ordinary (and painstakingly diverse) individuals from every corner of the British Isles. These seemingly random individuals random represent a cross-section of society (although shallow nobheads seem to be a bit over-represented). The castle is vast and labyrinthine, as are the paths through this treacherous landscape ...
The Faithfuls are ready to make friends, stab each other's backs, and possibly win huge sums of money and even become famous into the bargain. Imagine a hen party Murder Mystery Weekend with Harry Potter cosplay. Pitted against each other, these law-abiding folk find their values challenged. Relationships are tainted by distrust and fear. Betrayal, hate and bad faith take the upper hand as the rules that hold society together rapidly start to crumble. And this is when they are denied access to social media.
Each night one of the group is 'murdered' by the dark, secretive forces within - the Traitors. Their actions are directed by the sinister Manny Clawdwinkle whose remarkable wardrobe (one might suppose) is large enough to fill every room in the castle. Will the murderous Traitor be unearthed before the Faithfuls finally rip each other to shreds? And do that many people in society really have so much cosmetic surgery? Phew!

Huw Dunnit