An unknown host invites a disparate group of people to an isolated location, and then informs them of the plan to kill them one by one; accusation and counter-accusation is high on the agenda, but the deaths come regularly no matter what our invitees do. That The Invisible Host (1930) by husband-and-wife team Gwen Bristow and Bruce Manning shares some core DNA with And Then There Were None (1939) by Agatha Christie isn’t in doubt. What makes this fascinating reading, quite apart from its brisk pace and very entertaining setup, is seeing how different minds develop the same base ingredients.