Rachel Winters Achilles is Hercule's "twin." I just finished rereading this book because I'm a big AC fan, and I realized I had not read it in years. Now, I know why. It's possibly among AC's 10 worst books and by far, in my opinion, the worst Poirot/Hastings book. It is third or fourth at the beginning of her career and I suspect she was trying things out. She had not decided exactly what to do with Hastings so she portrays him as a bumbling idiot. She got the nuance better in later books when she went with the lovable fool persona. I skimmed a lot.