[Note: The Ghost Writer opens Fri., March 5 at Regal Cinemas' Park Place Stadium 16 in Pinellas Park before expanding into more theaters next week. (You can check showtimes here.) For more reviews of the biggest new releases, check out the Daily Loaf Movie Review Index.]

It's impossible to talk about The Ghost Writer, the taut new political thriller from Roman Polanski, without also wading into the moral swamp of the director's legal problems. For starters, Polanski's recent arrest on decades-old American rape charges forced the filmmaker to complete some of post-production while under house arrest in Switzerland. Knowing that, you can be sure that some conservative viewers are going to read into the film a potent anti-Americanism that can be marginalized as tit-for-tat retribution. Whatever your view of Polanski the man, or of geopolitics in general, there is no denying that The Ghost Writer is a potent mystery anchored by a terrific performance by Ewan McGregor.

McGregor stars as an anonymous ghostwriter hired to fix a first draft of the memoirs of embattled former prime minister of England Adam Lang (Pierce Brosnan). It's one of those gigs that's both too good to be true and far more trouble than it's worth: One month's work for an absurd amount of money; just don't end up like the last guy hired to do the job and wash up dead near your employer's Martha's Vineyard beach house after (apparently) committing suicide. McGregor takes the job and flies to America, where he meets Lang and his two main handlers, his wife (Olivia Williams) and his platinum-haired assistant (Kim Catrall) — a female odd couple looking after their man while quietly seething over each other's existence.

Almost as soon as McGregor lands in the USA, a major scandal involving war crimes (waterboarding, extraordinary rendition, etc.) erupts around Lang, threatening to land the former PM before the world criminal court. It's a good thing for Lang that America is one of the rogue nations that refuse to recognize the jurisdiction of this legal body. (Other non-participants: Iran, North Korea, Iraq and Israel.) Tensions run high in Lang's inner circle (he faces arrest if he returns to London), which is really slowing down work on the memoirs. Meanwhile, McGregor's editors see all the splashy headlines as their chance to recoup the crazy amount they paid for the book and cut his deadline down to two weeks.

As the ghostwriter learns more about the PM — and especially about his wife — he becomes more and more suspicious of the couple. Where the film leads I won't reveal, except to say that The Ghost Writer is surprising right up to the final shot, which is some kind of mini-masterpiece all its own. Polanski wrote the screenplay with novelist Robert Harris (whose novel The Ghost provides the source material), and the film's plotting is both complex and satisfyingly tidy. Polanski has previously proven himself adept at tackling labyrinthine mysteries (see: Chinatown), but it's been a while since the director has produced work of this quality.

The Ghost Writer was filmed in Europe with Germany standing in for Massachusetts (for obvious reasons), but the effect is convincing. As is every single performance in the movie, including all those I mentioned plus Tom Wilkinson as a shadowy college professor and Robert Pugh as a former British government official with a commitment to justice. I know that some will reject The Ghost Writer out of disgust for Polanski and his past crimes or because of the film's political leanings, and that's understandable to some extent. But it's also a shame, as The Ghost Writer is easily the best film thus far in a very young 2010.