This book was not written by Agatha Christie, it is a novelized version of the play of the same name that she wrote. This matters because the book does not read as a conventional Agatha Christie novel. The story takes place in the house of a famous physicist, Sir Claud Amory, who asks Poirot to help him because he thinks someone in his household will betray him.

I enjoyed the book but I read it as a play, and not as a crime fiction novel. Although I am sure this works much better watching it as a play, I enjoyed reading the characters and I truly believed any of them had reasons to be the culprit. Nevertheless, I am confused by the reading order as Poirot refers to the "killing of Lord Edgware" in this story, and that book is supposed to be the 9th of the series whereas this the 7th.