Yes, it's the nudie Ewan McGregor film. Yes, another one. But the NC-17 rating is absurd -- the nudity is casual and brief, the sex is consensual and mostly under cover of clothing or blankets; there's nothing pornographic about this soft, sly little film based on Alexander Trocchi's 1954 novel. Where it's disturbing is in McGregor's (Big Fish) challenging, defiant performance as Joe Taylor, a hand on a coal barge in 1950s Scotland. Joe and his boss, Les Gault (Peter Mullan: Criminal), find the nearly naked body of a young woman floating in the canal one morning; soon after, Joe begins a clandestine sexual liaison -- furtive grappling can hardly be called an affair -- with Joe's wife, flinty Ella (Tilda Swinton: The Statement). Did one event prompt the other? Giles Nuttgens's washed-out cinematography and writer/director David Mackenzie's cool distance -- we never entirely know what's going on in anyone's head -- lend a beautifully grim air of mystery to Joe's tale, which now turns to flashbacks of a more comfortable life as a novelist with a beautiful and attentive girlfriend. Is it all a dream inspired by the mysterious dead woman, a writer's fantasy of who she might have been? Is Joe merely playing at being the working-class bargeman, the dallying with Ella merely a game? McGregor dares us to sympathize with his Joe, and it becomes more a taunt as he slowly reveals Joe's cold heartlessness. That we don't entirely hate Joe in the end -- and instead struggle to understand him -- is a testament to McGregor's immense capacity for bringing the audience as deeply into a character as he himself delves.