Writing a Continuation Novel is never easy. Few authors get it right the first time. Kingsley Amis and John Gardner got their Bond novels bang on the spot; Raymond Benson barely scraped through, while the less said about Sebastian Faulks-Jeffrey Deaver-William Boyd, the better. Similarly, Sam Llewellyn did a much-more-than-decent job with his continuation of the Navarone Saga.
However, Sophie Hannah, in her first—and hopefully last—Poirot novel, The Monogram Murders, messes it up horribly. Sacre tonnerre, but this is not Poirot at all!!! The backstory, told in flashback mode, is mildly interesting and might have turned out finely in Dame Commander Christie's hands, but here it falls utterly flat. A convoluted plot, cardboard characters who act out of character for the most part, half-baked motives, underdeveloped plot points, an unsatisfactory ending: in short, this one is an almost unmitigated disaster fans of Poirot and Christie in particular and the world in general could well have done without. What's more appalling is an irritating douchebag of a secondary hero, who renders the proceedings even more tedious.
Eh bien, give it a shot only when you have nothing else to read. And then go back to the originals to rinse your mouth thoroughly of the aftertaste.
P.S.: I wonder what kind of a travesty Sebastian Faulks has turned out in the latest Jeeves-Bertie Wooster novel Jeeves And The Wedding Bells. If the reviews so far are anything to go by, Faulks deserves a very unpleasant and long-drawn-out death.