Christie wrote a courtroom thriller that works because the audience is put in the position of a jury: you hear the evidence as it is given, you form a view, and the play spends its final act taking that view apart. It is tighter and colder than most of her country-house work, and it is one of the few of her plays where the ending genuinely lands on people who think they know her patterns.
The best-known production stages it inside a chamber built for actual civic business rather than for theatre, and that is not a marketing line. The room has a public gallery, benches, tiers and a well, and the production uses them as the courtroom, with the audience seated as spectators and, in some seats, as the jury itself. Seating in a room like that is nothing like a standard theatre, and the categories reflect real differences: bench seating without backs, tiered gallery seats looking down into the well, and a small number of seats placed within the action.
That has consequences worth weighing. Seats in the jury or on the floor of the chamber are a different experience with a different relationship to the actors, and they are also more exposed. Gallery seats give you the whole room and the geometry of a trial but sit further back and higher. Bench seats without backs are exactly what they sound like across a two-and-a-half-hour show.
Where the play is staged conventionally, in an ordinary theatre, all of this collapses into a normal seating decision, and the venue on the listing tells you which situation you are in.
Runtime is around two hours and thirty minutes with an interval. PickStub is an independent marketplace and is not affiliated with the producers of this play, the Agatha Christie estate, or the venues staging it.