Just a few minutes before I started this, I read the version of the story starring Parker Pyne instead of Poirot. Maybe it's just that I found the mystery a little less convoluted on second read, but I think the extra star for this version is more likely down to character: Poirot is simply more entertaining than Pyne. Perhaps it's not a fair comparison, given that I've only read one short story of the latter, but the fact remains: the smug, compassionate little Belgian improves the story for me.