Anna's POV:

Lady Martha Silver arrives at the villa on a Tuesday morning with the specific energy of a woman who has decided something and is now executing it at speed.

"Three weeks," she says, when she is seated and Karl has produced tea. "The full moon falls on a Saturday. That is the night." She looks at me across the table with the expression she now uses when she has decided to be direct rather than measured. "Is that sufficient time for you to be ...