In cinema as in life, there's nothing quite like a fiendish mystery to keep you awake at night.
Movie storytelling at its finest keeps the viewer's brain ticking over long after the credits have rolled, deliberating the ins-and-outs of the story and its characters ad nauseum.
These 12 movies each presented a mystery or a question which has persisted in viewers' minds ever since, from plot elements which were intentionally withheld from audiences to ambiguous endings which have just a couple of possible explanations.
Of course, the vast majority of these mysteries are as effective as they are precisely because the ambiguity is so steadfast and the filmmakers themselves have (mostly) refused to comment one way or another.
But human curiosity being what it is, film fans can't help themselves but debate these burning questions until the end of time. Whatever side of each argument you fall down on, these movies just wouldn't be the same without their delicately-laid enigmas...