It's not uncommon to watch a film and see what's coming next from a mile off - movies can be pretty predictable after all, and many of them follow so closely to genre conventions that they might as well be a carbon copy of their predecessors. On the flipside, sometimes a movie comes along with a plot which confounds us for all the wrong reasons, where the narrative is so badly written and confusing that it's almost impossible to make any sense of it. But bad writing is hardly praise for a complicated plot which doesn't know its proverbial arse from its elbow - the real challenge for any filmmaker of merit is to deliver a complex plot which gets the viewer scratching their head and thinking while still retaining an internal logic and plausibility. These are the films which tackle complex themes with a maturity and integrity in a manner which is worthy of respect, even as we sit there struggling desperately to comprehend what it is we've just watched. The following list covers ten such films; movies with complex and intricate plots which truly made our heads hurt as we tried to unravel the meaning. Make sure you put your thinking caps on before pressing play.