The Killings at Kingfisher Hill
Sophie Hannah
"After making her astonishing announcement, the woman with the unfinished face clammed up so determinedly that further debate proved impossible. Ignoring the outraged splutterings of Alfred Bixby (“The very idea, M. Poirot! A murder on a Kingfisher Coach Company motor-coach? Such a thing would never happen!”), Poirot ordered the driver to stop so that he could take the unhappy woman outside and attempt to get to the bottom of it all."