Ten people is the sweet spot. Big enough that the table splits into factions, small enough that everyone gets questioned. Here is exactly what to buy, what to print, and what to do the hour before, for a party where nobody has to host.
That is the whole list. No props, no costumes required, no name tags. A candle helps.
The kit is one PDF, printed single-sided on plain paper. For ten players you print the eight core character cards and one optional pair, eight evidence cards, envelope labels, three petition cards, a setup sheet, and a rules card. About twenty pages.
Whoever sets this up plays. You have not read the solution. The Conductor has it.
Ten minutes of mingling in character. The toast. The death. Then three acts of about twenty-five minutes each, with the screen releasing envelopes on a timer and delivering in-fiction messages. After the first two acts the Conductor questions every guest by name and the table votes. After the third, petitions are counted, everyone makes a final accusation, and the Conductor reads what actually happened. Two and a half hours, give or take an argument.
One long table if you have it, so the screen is visible to everyone. Food that can sit out: a board, a big pasta, something people can eat with one hand while pointing with the other. Serve dinner during arrival and the first act. Dessert during the reveal.