Script versus novel
This was the first of the post-war novels to be adapted for the series and its established 1930s setting. In the years to come this would become a common occurrence - moving the plot of post-war novels back to that decade. Sometimes the transition is seamless (e.g. The Clocks, Mrs. McGinty's Dead), and sometimes not as much (Third Girl). Horowitz's script, I would say, falls somewhere in between. To begin with, the task of transforming a student hostel situation - post-war in its very nature - into a believable 1930s student rooms is not an easy one. Horowitz partly succeeds in that the 1930s student feel that we also got in the adaptation of 'The Case of the Missing Will' works quite well. He removes all the foreign students, including Mr. Gopal Ram, Akibombo, Elizabeth Johnston, Miss Reinjeer, Achmed Ali, Genevieve Maricaud, Jean Tomlinson and the two Turks (who, I assume, would be somewhat out of place as students in the 1930s - but, more importantly, they don't really provide important plot points, possibly apart from Akibombo, so it makes sense to delete them for time constraints reasons, too). A further change I don't quite understand is making all the residents of the hostel students - even Valerie Hobbhouse, who becomes a student of design and fashion. That seems a bit excessive, especially since the Series Five episode I mentioned (set at about the same time) covers the difficulty facing female students at universities. Anyway, I guess it works somehow or other.
As to plot changes, the list is actually quite long. First, we have the addition of Chief Inspector Japp (who replaces the book's Inspector Sharpe), and a subplot concerned with him coping (or not coping) at home in Mrs Japp's absence. He is eventually invited to stay with Poirot at Whitehaven - which, of course, gives room for some comic relief, like the bidet thing, but it all gets a bit too much, in my opinion. Especially that end scene in Japp's kitchen (faggot, phobie du faggot, spotted dick etc.). Second, the story is set around the 1936 Jarrow March (which occurred in October, not in April, as the lecture note at Hickory Dock seems to imply...a careless mistake), Sir Arthur Stanley becomes a leading Labour politician (and not a chemistry professor as in the novel), and Japp has a grudge against him because he investigated the death of his wife about ten years ago. Third, Miss Lemon's role is significantly expanded (which seems just right since her role is central to the story), and she is present throughout much of the investigation - and gets involved, too. Fourth, a couple of clues are removed partly as the result of the deleted student characters, including the silk scarf and the green ink. Fifth, Horowitz adds a subplot involving Customs and Excise, in which Sally Finch, the American student, gets a significant role. Sixth, the morphine that disappears was acquired by Colin McNabb, not Nigel Chapman as in the novel, probably in an attempt to widen the list of suspects (certain other additions, like Sally sneaking out at night and Len sneaking into Celia's room, attempt to do the same). Seventh, a further clue is added in the form of Valerie's peculiar stitch-work on a dress (and, of course, later on the rucksack). Eight, Patricia realises the connection between Nigel and Sir Arthur through a photo album at the hospital and not through conversations with Nigel. Finally, Horowitz adds the ever-present chase scene (this time at 'Hickory Road' tube station).
On the whole, even though Horowitz's changes are significant, the adaptation actually works as a more or less faithful retelling of the novel. The essential clues and plot points are retained, and even though the number of students is reduced, it's not something you would notice if you hadn't read the novel. In other words, apart from the odd anachronisms, including the student setting, the Fulbright Scholarship (not introduced until 1946) and the mistaken setting of the Jarrow March, the adaptation isn't half bad, considering the novel is very distinctly post-war.
Directing, production design, locations, soundtrack
Grieve's direction is as good as always, with a number of delightful references to the nursery rhyme and the mouse the student house name gets its inspiration from (notice, for instance, that both the opening shot of the living room clock and the shot of the clock in the denouement scene displays the time as one o'clock).
Hickory, dickory, dock,His direction works well together with Gunning's score, which repeats the 'Hickory, dickory dock' line. There is one issue with his directing choices, however. Several shots clearly reveal the identity of the murderer quite early on. Whether this is deliberate or not, I don't know, but it is quite evident if you know the story. The locations used for the episode include YHA, Carits Lane, London (the student house), Allen, the butcher, Mount Street, London (the place where Japp and Poirot buy meat), a car park entrance in Cartis Lane (the 'Hickory Road' station entrance), Brushfield Street, Spitafields (the store of Mr. Nicoletis) and Morden Station on the Northern Line (used as 'Hickory Road' station). See this link for photos.
The mouse ran up the clock.
The clock struck one,
The mouse ran down,
Hickory, dickory, dock
Characters and actors
It's great to get some back story on Miss Lemon and her sister. Notice that Horowitz has given Mrs Hubbard a first name, Florence, to match Miss Lemon's (Felicity). Although I dislike some of the comic relief with Japp, it's nice to see their friendship develop further. Of the guest actors, I am most impressed by the fact that the casting director managed to find an actress so strikingly similar to Pauline Moran (Miss Lemon) as Sarah Badel (Mrs Hubbard). Not even that, Badel manages to match her in mannerisms and complement her just as in the novel. A delight to watch. Of the students, there are no real stand-outs, apart from Jonathan Firth (Nigel Chapman) of course. And naturally, there's the fun of watching a very young Damian Lewis of later Homeland fame.