The Silent Pool Av Patricia Wentworth

First she felt herself being pushed downstairs. Then there was the bowl of poisoned mushroom soup. Finally the tampered-with tablet amongst her sleeping pills was the last straw. Adriana Ford, famous actress and mistress of the house decided to call in Miss Silver. And Maud Silver, with impeccable logic, pointed out that the person who was trying to kill her must be a member of her own household. And then the murders started...