In this mystery novel from 1959, a young couple with a baby rents out a room in their house to Miss Trub, a middle-aged spinster who seems to dote on young Joy. But one day, coming back from a night out, they find the house full of gas - with their baby and Miss Trubb inside. During the subsequent investigation, the couple find out that years before, Miss Trubb had been accused of killing her illegitimate child. Somehow the couple can't believe that Miss Trubb would have harmed either her own child or baby Joy, and they set out to investigate her antecedents, with the help of the distinguished barrister who defended her at her trial. This takes them back into the lives of both Miss Trubb and her sister before and during WWII, and they soon realize that there are many unanswered questions. Was Miss Trubb really the mother of the baby she appeared with one day? What was her sister up to during her Art School days? And why do they have the uneasy impression that they are being spied upon?
I enjoyed the book and I had not anticipated the ending. Miss Trubb's fugue states and stubborn disinclination to help with her own defense were undoubtedly necessary to keep the story going, but it got a bit tiresome towards the end. Reg and Mavis were a sympathetic pair of amateur detectives, decent folks who just can't stand to see an innocent woman suspected of heinous crimes.