Sabotage demands the viewer's attention. It opens with a dictionary definition of Sabotage, forcing the viewer to read something and then immediately relate it to the rapidly edited sabotage of a power station. This sequence, which sets off the first act of the film, takes place in maybe a minute, maybe less. Charles Frend's editing is rapid and fluid; it's ever moving, ever graceful.
This first act almost seems like a stage play, establishing the principal cast members. There's suspicious husband Oskar Homolka, his young wife Sylvia Sidney, her younger brother (the reason why she's married to a troll, even if he's nice) Desmond Tester and, finally, the too friendly shop keep from next door John Loder.
Over the film's first sixteen or so minutes, Hitchcock creates an odd domestic short. Sidney doesn't question Homolka, who maybe is just suspicious generally and not explicitly.
But then everything changes–the film follows Homolka and Loder on their separate paths, with Sidney and Tester sort of the spheres they're exerting gravity on. Hitchcock is very expressionistic during the first half of the film; the odd domestic situation, while apparently tolerable, is a little off.
Later on is when Hitchcock opens up, when Sabotage has its first amazing sequence. Then there's a lull and then the second amazing sequence. The second one is nearly silent. The finale, which is intricate, is just gravy.
Sidney and Homolka are both fantastic. Loder's strong. Excellent supporting cast.
Great script, great direction, great Bernard Knowles photography–Sabotage's entirely phenomenal.