Brimming with wartime secrets and family quarrels, Death at One Blow is the second in Henrietta Hamilton's Sally and Johnny Heldar mystery series. Needing a break from summer in the city, Sally and Johnny Heldar leave London for the countryside. Tasked with sorting out two jumbled personal libraries in a country estate, the couple are looking forward to a holiday break filled with books, fresh air, and reconnecting with long time friend Sir Mark. But upon their arrival, the Heldars become privy to tensions within the house, and soon the pair find themselves at the centre of another mystery.