Script versus novel
Nick Dear's script is impressively true to its source material. His changes are largely aimed at simplifying the plot elements for a ninety-minute time slot. Obviously, the setting is moved from the post-war years to the late 1930s, in tune with the time frame of the television series. The transition is more or less seamless. Moreover, Dear deletes some of the village characters, including the Wetherbys, their daughter Deirdre Henderson and Edna (witness / Joe Burch's lover). In Edna's place, Mrs Sweetiman of the post office becomes Miss Sweetiman. She has a secret meeting with Joe Burch in the woods. Also, Dear places less significance on the red herring of the anonymous letters to Dr Rendell, and the nature of the these. A further change concerns the crimes in Pamela Horsfall's newspaper article. These are reduced from four to two (Janice Courtland and Vera Blake are deleted). This is an improvement on the novel, as the two extra crimes did nothing to elucidate the plot. Finally, the character of Maude Williams is given a different backstory, turning her into something of an independent sleuth with a personal vendetta rather than Poirot's agent (in fact, she disguises herself as a survey conductor instead of working for the Wetherbys). Maude also becomes a love interest for James Bentley, and Dear adds a nice match-making end scene (reminiscent of quite a few of the later Poirot episodes, e.g. Sad Cypress and The Clocks). Dear makes some other minor changes as well, like introducing the brilliant character of Ariadne Oliver earlier than in the novel, and having Mrs. McGinty's niece live in McGinty's old house rather than somewhere else. All in all, the adaptation remains faithful to the novel, maintaining much of both its humour (including nearly all of the Mrs Oliver dialogue!) and its bleakness.
Directing, production design, locations, soundtrack
Ashley Pearce's direction takes some getting used to. I remember the first time I watched this episode I was just extremely annoyed by the constant use of out-of-focus close-ups and blurry shots, and I know some fans still feel this is one of the most poorly directed episodes of the series. With time, though, I've grown to appreciate the artistic choices somewhat more than I did initially. The slight 'glow' of the shots actually add to the atmosphere of the adaptation, and I enjoy the many overhead shots (particularly the crane shot of Poirot arriving in Broadhinny, which gives us the feeling that we are peering into not only Poirot but the lives of all the people in the village). In sum, then, the direction actually succeeds in creating a particularly eerie and dark atmosphere that goes well with both the original novel and Nick Dear's script. I also have to give credit to the production designers this time around. Not only are these sets perfect to look at (and contribute to create the atmosphere), but they have accurately taken the specific descriptions from the novel into account. For instance, the sugar hammer is exactly as described in the novel, and so is the Carpenter house. The locations include Richmond Theatre (where Robin Upward's play is performed), the village of Hambleden in Buckinghamshire (previously seen in Evil Under the Sun and Sad Cypress), Horsted Keynes Station on the Bluebell Railway in East Sussex (Broadhinny Station) and 'St Anne's Court' in Chertsey (Carpenter's house). The roof area of the latter house would later be seen in Three Act Tragedy, and the entrance hall was used as part of the flat belonging to Halliday in 'The Plymouth Express'. Stephen McKeon's soundtrack is effective for the atmosphere of the episode, and several tracks are available on his website. I particularly love the minute references to Gunning's Poirot theme that were also hinted at in the score for Cards on the Table.
Characters and actors
It's an absolute treat to see the relationship between Poirot and Mrs Oliver develop further. She is a perfect Hastings substitute while at the same time providing Poirot with something completely different. Scriptwriter Nick Dear made the clever decision of keeping most of Ariadne's lines from the novel, which leads to some humorous interactions. I particularly enjoy the discussion of Robin Upward's play adaptation, but most of all I think her arrival scene (even down to the apple core from the novel) is especially well done, and her driving (with Poirot as a passenger) brings to mind all the scenes in the earlier episodes with Hastings and his race car. As I've said before, Zoë Wanamaker is the perfect Mrs Oliver to match Suchet's Poirot. It's also nice to see David Yelland back as Poirot's valet George (he comes across exactly as in the novel), and to see Richard Hope return as Superintendent Spence (previously seen in Taken at the Flood, he was sadly deleted from the adaptations of Hallowe'en Party and Elephants Can Remember. As for the guest actors, there are several good performances here, but the stand-out has to be Paul Rhys as Robin Upward. What a performance, especially towards the end of the film.