Through this Christie reread, I've discovered that some of my favorite books are the ones where she abandons the fussy, arrogant Poirot and the cotton-wool-over-steel Miss Marple for a one-or-two-off character study of a murder. Crooked House, And Then There Were None, Towards Zero, Endless Night have all ended up as favorites. Perhaps my least favorite part of the Poirot novels is Poirot?
Not really, but he can be truly irritating.
Anyway, this is another of her stand-alones, featuring a character named Dr. Calgary who, recovering from amnesia, realizes that he is the alibi witness for a young man, Jacko, who has been convicted of murder, and died of pneumonia in prison. He goes to the family of the deceased, Jacko's adoptive mother, and announces that he has cleared Jacko of wrongdoing, thinking they will be pleased.
The flaw in his reasoning becomes quickly apparent - if Jacko didn't do it, who did? Which one of them - for the victim had a quintet of adopted children - is responsible for taking a poker to mum's head? Was it one of the children? Their spouses? The husband who has fallen in love with his young secretary? The devoted house keeper? As Dr. Calgary digs, more bodies begin turning up.
I've read enough of these, that the solution wasn't startling, but it was well-done.