Script versus short story
The adaptation is more or less faithful to its source material, but there are several important additions and expansions of plot lines. First, there's the opening scene in which Poirot, Japp and Hastings are watching G Men (1935) in a cinema, a typical American gangster film. In a way, the film metaphor of the plot is sort of implied by Poirot in the short story, remarking to Hastings that the details of the case will remind Hastings of his "favourite cinema". The scene is also reminiscent of the magician's show the three attended at the opening of The Disappearance of Mr Davenheim. Second, the precense of the the FBI agent (Burt) is significantly expanded, and he is portrayed as a typical caricature of an American who is completely uninterested in Poirot's talent. Third, Miss Lemon is added to the story (like in most previous episodes), and she gets to investigate by posing as a journalist of the Ladies' Companion (a truly delightful scene to watch). Fourth, the storyline of Elsa Hardt (called Elsa Hart in the adaptation) is somewhat changed. Her real name is Carla Romero in this one, and she has fled America with her real (?) husband. She has taken up work as a nightclub singer (the club has a cat as a logo - a reference to the cat in the short story) and is using her pseudonym Elsa Hart. Fifth, there's a rather dodgy manager of the night club added to the mix. Of minor changes to note, there's the fact that Stella Robinson doesn't look like Carla Romero (that plot point was too much of a coincidence to be believable anyway), and Poirot and Hastings break into the Robinsons' flat while they are home (Hastings distracts the couple, Poirot tampers with the lock) and don't wait for the mafia guy in their flat but enter through the dustbin stairs. All in all, however, the changes made to the story make complete sense and the result is a rather enjoyable episode.
Directing, production design, locations, soundtrack
Spence does a decent job of displaying the spy angle of the story, with several shots out of windows, behind doors etc. As to sets, there's a clever recreation of a New York night club. The set seems to be deliberately artificial, with the New York skyline in the background clearly a painting of sorts, and the director underlines the fact through a camera shot that glides through the outer wall of the nightclub. The building used as the block with the cheap flat is in reality an address in Duchess of Bedford Walk in Kensington. The soundtrack for this episode (and in fact most of the Series Two episodes, together with Fiachra Trench) is by Richard Hewson (who stepped in as Gunning was unavailable) and has not been released, as far as I know.
Actors and characters
It's nice to see Miss Lemon as a sleuth again. Personally, at least, I really think the expansion of her character in the series has worked brilliantly. Normally, the tasks she is given by Poirot seem just natural for her to investigate (addresses, names, dates etc). Perfect. The guest actors do a nice job of portraying their characters. Samantha Bond (Stella Robinson) is a standout, and that's not just because she later became an example of all the Poirot actors who have achieved great fame. American actor William Hootkins (Federal Agent Burt) is also quite good, almost managing to create a believeable character out of a stereotype.