Why Agatha Christie’s mousetraps still beguile us, even if the films aren’t always killer

After two relatively faithful adaptations of Agatha Christie’s “Murder on the Orient Express” and “Death on the Nile,” director-star Kenneth Branagh goes wildly off-book with “A Haunting in Venice,” which arrives in theaters Friday. The attempt to turn Poirot into a plausible romantic lead, or at least to suggest a backstory awash in thwarted passion, has always slightly felt designed to flatter Branagh’s ego — and also to deepen and humanize a character often reduced to the sum of his attributes and mannerisms: the mustache, the egg-shaped head, the “little gray cells of the mind.” Christie famously grew tired of Poirot herself, and often resented him for being more of a reader favorite than her other great sleuth, Miss Marple. “Evil Under the Sun” has been popular with Hollywood; “Hercule Poirot’s Christmas” would be a great holiday film; and I know you are a big fan of “Five Little Pigs,” Justin. David Suchet in the 2010 “Masterpiece Mystery” adaptation “Poirot: Murder on the Orient Express.” CHANG: While there has already been a Suchet-starring TV adaptation, I would love to see a big-screen version of “Five Little Pigs,” of which the late crime novelist and Christie scholar Robert Barnard once wrote, “The present writer would be willing to chance his arm and say that this is the best Christie of all.” I don’t know if I’d chance my arm, but I know the novel is an absolute masterpiece — not only one of the most beautifully plotted of Poirot whodunits, but also by no small margin the most beautifully written.