The Summer House Party by Caro Fraser

In the gloriously hot summer of 1936, a group of people meet at a country house party. Then a shocking death puts an end to their revelry, changing everything in an instant.
'Fraser keeps the reader hooked with the twists of her protagonists' love affairs, but the real star of this book is her portrait of a disappearing life, as Sonia Haddon and ilk face war with varying degrees of courage' The Sunday Times.