This is the final book I’ve read for this year’s Read Christie challenge. I had intended to read it in November, but didn’t have time. I’m glad I’ve still managed to fit it in before the end of the year because, although I don’t think it’s one of Christie’s absolute best, I did enjoy reading it.

Norma Restarick is the ‘third girl’ of the title. The term refers to the practice of two girls who are living together in rented housing advertising for a third girl to take the spare room and share the rent with them. Norma crosses paths with Hercule Poirot when she approaches him for help because she thinks she may have committed murder – but after meeting Poirot in person, she flees, saying she’s made a mistake and he is too old to be of assistance.

Concerned – and insulted – Poirot tries to find out the reason for Norma’s visit to him and learns that the girl is acquainted with his friend, the mystery writer Ariadne Oliver. This makes it possible for Poirot, with Mrs Oliver’s help, to track down Norma’s family at their home in the country and the two girls she lives with in London. But Poirot is still confused. Norma says she thinks she has tried to poison her stepmother because a bottle of weed killer has been found in her room, yet she has no memory of actually doing it. It’s also not the only time Norma has experienced gaps in her memory. Convinced he doesn’t have all the facts and that the murder Norma originally referred to was not the attempted one she’s now confessing to, Poirot begins to investigate.

A common theme in Christie’s later books seems to be that society is changing and the world is moving on and she doesn’t like or understand it. Published in 1966, this book is firmly set in the 1960s and the older characters take every opportunity to complain about the fashions (particularly men with long hair), the music, the culture and what they see as rampant drug use amongst young people. I found this interesting as it gives the book a very different feel from the earlier Poirot novels. I think Poirot, like Christie herself, probably felt much more at home in the 1930s!

Third Girl is also unusual because for most of the book we don’t know if a murder has actually been committed and if so, who the victim is. This makes it less of a conventional detective novel and more of a psychological study of Norma Restarick. As we learn more about Norma’s past, there’s a real sense of her vulnerability and how she could be being manipulated by other people. Even when the true nature of the crime that needed to be investigated became clearer, I still didn’t correctly guess who the culprit was – and to be honest, I thought it was quite an unconvincing solution, which relied on several of the characters being very unobservant.

What I did love about this book is that Ariadne Oliver plays such a big part in it from beginning to end. She is often said to represent Christie herself and gives her a chance to comment on the writing of detective novels! It’s always nice to see her pop up in a Poirot mystery and I wish she was in more of them. In Third Girl, Mrs Oliver adds some humour to the book, as well as inadvertently providing Poirot with some of the key clues. Poirot is also present from the beginning of the book, rather than appearing halfway through as he often does.

I’m pleased to have completed eight of the twelve monthly reads for the 2024 Read Christie challenge. I’m looking forward to joining in again in 2025!