It is far from profound to say that films are often intentionally challenging and not only worthy of but inherently designed to require a rewatch (or seven).
The best directors, living and past, want little more than their films to be interpreted, mulled over and exhaustively examined time and again - and what better way to do that than to make repeat viewings the key to understanding the film itself.
Some enjoy furnishing their features with little hints and tricks and subtleties that only become apparent once the viewer knows all there is to know - say, a twist or a high-stakes piece of final act drama; others prefer to layer their films with deeper themes and existential concerns; others still relish convolution and a tight intricacy that needs to be unpicked element by element.
Whatever their tools, filmmakers have succeeded time and again in creating magnificent works of cinema that simply cannot be put down, leading to special editions and commentaries and research papers and entire library stacks of books dissecting their work.
Though by no means a comprehensive list of the films that need a second look, this article nonetheless collects together some of the most fun, intriguing, puzzling or downright ingenious features that cinema has to offer.
Be warned: weapons-grade spoilers ahead.
10. Shutter Island (2010)
Set in the 1950s and based on a story by Dennis Lehane, Martin Scorsese's neo-noir thriller Shutter Island is replete with the kind of wiseguy style that made Scorsese's name, but also fast-moving, paperback genre thrills that are definitely not par for the course.
Leonardo DiCaprio's Deputy US Marshal Teddy Daniels journeys with his partner Chuck Aule (Mark Ruffalo) to Shutter Island, a sinister island asylum where dangerous inmate Rachel Solando has disappeared from her cell.
Once on the island, the roles of patients and doctors seem fluid and uncertain, Teddy begins to suffer from migraines and a conspiracy unfolds. Disturbing fiery dreams of his wife are matched by the revelation that her killer, Andrew Laeddis, is on the island.
The twist ending is not hard to grasp and ties up Shutter Island's narrative quite neatly: Teddy is actually the inmate Laeddis, who was incarcerated for murdering the wife he has nightmares of. But it is the small details and double-meanings throughout that make second viewing mandatory.
The nods and ticks or the acting and cinematography play a sort of sleight of hand for the viewer, so that while we suspect we are being tricked throughout, the truth is staring out from every shot. Subtle, clever details are woven in throughout, meaning that what may appear as, say, the lazy uncooperativeness of the prison guards in the first viewing, becomes the actions of men merely babysitting a rampant imagination in the second.