Tactical Unit: Comrades in Arms (2009)

The fourth of five TV Movies set after Johnnie To's PTU (2003). It starts out with a superb scene wherein the geography of the city itself sets the tone perfectly for a deeper exploration of the dangerous rivalry that exists between Sam and May and the men under their command.
They're later shipped out of the city, into the mountainous region on the trail of a gang of bank robbers, so even the locale tests them, forcing them to be ever-alert to the other's attempts at one-upmanship.
The individual parts of the story aren't complex, but they're nicely arranged and the way in which they all come together is extremely satisfying to watch. Indeed, it's not until that moment that the real power of the film hits.

3½ church windows out of 5