If you’ve seen Dunkirk or read the reviews you know about the land-sea-air thing. The Guardian‘s Mark Kermode has explained the scheme, at least as he sees it:

“Ingeniously, these strands play out over three different time periods; one week, one day and one hour respectively. As the stories interlace, with boats, boots and planes converging at Dunkirk, so time itself is variously compressed and elongated in Inception-like loops, conjuring shifts and reversals as complex — yet still crucially as clear — as those of Nolan’s 2000 psychological thriller Memento. For all its visual splendor, Dunkirk is a masterclass in dextrous temporal elasticity, a recurrent theme for Nolan, sparked by his love of Graham Swift’s novel “Waterland” and explored most recently in Interstellar.”