You're too old. Nobody told me you were so old. I really don't want to be rude, but - there it is. You're too old. I'm really very sorry.
By 1966, Hercule Poirot would have been well over 100, and he only appeared in two 'new' novels after Third Girl (Curtain was written in the early 1940s). Agatha Christie was also in her mid 70s, and about as able to understand the youth culture of the 60s as her detective. Only four years separate Third Girl and The Pale Horse, but the societal changes of those years are highlighted by the later novel's urban setting. Mark Easterbrook spends most of his novel in a 'timeless' small town or a less clearly dated counter-culture neighborhood; Norma Restarick is a creature of the mid 1960s.
Miss Restarick arrives on Hercule Poiroit's doorstep, bedraggled and confused and thinking that she may have committed a murder. More through coincidence (in the shape of Ariadne Oliver) than the famous little grey cells, Poirot learns that she's the daughter of an executive who abandoned her and her mother 15 years earlier and has recently returned to London with a new wife and is now running the family business. She's a 'third girl' - an extra roommate sharing a flat with her father's secretary and an art gallery employee. Norma remembers bits of things - holding a bloody knife after seeing a fight in the courtyard, melting faces, the apparent suicide of her upstairs neighbor - and thinks she may be responsible. She isn't, of course, and the first time I read Third Girl (at least 20 years ago), the solution was a surprise.
As I said above, Christie didn't seem to "get" the 1960 (I think that's why she retreated to a more rural and timeless setting for her next novel), and yet this is one of my frequent re-reads. There's something about the overdone, slightly garish view of the 1960s that makes me think of watching movies on UHF channels as a kid in the 1970s - maybe that's the appeal. It's also a very well plotted, and features Ariadne Oliver, my favorite Christie character. I also find Christie's attitude towards 'modern girls' fascinating and perhaps a bit hypocritical. She seems to say that home and children are the best - or even only - option for young women, and yet she was a career woman who divorced when her only daughter was young, and an adventurer who took a round-the-world trip (and was one of the first Britons to surf standing up) with her first husband and went on several archaeological expeditions with her second. I'd never noticed those contradictions before, but they don't detract from my enjoyment of Third Girl.