Nevermind plot discription (you'll likely learn more reading a paragraph long historical synoposis), let me just cut to the chase like this film supposes to do, and affirm what's ineffecient in Chrostopher Nolan's otherwise superficially handsom WWII production.

Dunkirk is non-linear in shifting between three totally different time-spans which converge at its climax. Unfortunately that non-linear shifting is crafted haphazardly to play as randomly spliced discombobulating vignettes of pretty cinematography and authentic costume design in incoherent juxtaposition with nearly no character distinction, plot progression, sense of geography, or composed shot choreography for situational bearings in edit. It's entire narrative momentum comes exclusively from its sound design and most specifically from Hans Zimmer's musical drive and orientation.

Nolan's whole gimmick here is to present an arbitrary mystery to confuse the audience with lack of narrative structure instead of tell a compelling human story. The screenplay must have been about twenty-five pages randomely shuffled, then ripped into quarters, and then taped back together in total disregard for even sentence sequencing. If the on screen stand-ins for characters are supposed to know where they're at in relation to every given circumstance, and what goal they're moving toward, then so too should the audience without constantly questioning such superfluous allignment in perplexed detection for half the run time of the film.

Ultimately, Dunkirk is like 1 minute 45 seconds worth of plot for a perfectly beautiful IMAX shot commercial, presented in its ten-fold raw footage assembly cut of 1 hour 45 minutes, and then tasking Hans Zimmer to "make it work" as a feature (which he miraculously kinda does). So basically props to Hans, and an eye roll to Christopher Nolan.

Still a pleasure to blankly look at and listen to though. So credit due there.