Don't Open the Door

Don't Open the Door is a 1945 mystery thriller novel by Anthony Gilbert, the pen name of British writer Lucy Beatrice Malleson. It is the fifteenth in her long-running series featuring the unscrupulous London solicitor Arthur Crook, one of the more unorthodox detectives of the Golden Age. It was published in the United States with the alternative title Death Lifts the Latch.

Synopsis
On a foggy night, nurse Nora Deane heads to the house of her latest patient, an invalid Adela Newstead. Mrs Newstead seems terrified and once alone asks Nora to make contact with a man named Herbert without letting her husband know. But the next morning Mrs Newstead is dead. Nora then contacts Herbert and finds out he is the late woman's brother, who suspect there is foul play involved.