This was just delightful. Tuppence is such a great character, and I thoroughly enjoyed Christie's humor about aging. It also held a twist that I really didn't see coming until right before the reveal, which is refreshing. 
 I've come to really appreciate the fact that Christie doesn't pretend that clues are super mysterious omg when they are pretty obvious. The suspense of her books don't rely on her readers being purposefully dense, and the characters and storytelling are so good that I'd read them even if I wasn't hanging on to solve the mystery. I've been on a Christie kick lately, but this has been my favorite so far.