Director Roman Polanski has had his share of troubles.

From the horrors of the Manson murders that claimed the life of his wife to his own legal difficulties over sexual assault charges, Polanski at times seems to be the cinematic equivalent of Joe Btfsplk. (Apologies to those unfamiliar with “Li’l Abner.”)

But at age 76, Polanski (“Rosemary’s Baby,” “Chinatown,” “The Pianist”) remains a formidable filmmaker. He completed the post-production on his latest, “The Ghost Writer,” while under house arrest in Switzerland.

“The Ghost Writer” is an intriguing and polished paranoia thriller based upon the novel “The Ghost” by former BBC TV reporter Robert Harris (“Enigma”).

Ewan McGregor (“Amelia”) portrays an unnamed veteran ghostwriter who is hired to rework the awkward memoirs of a one-time British Prime Minister, Adam Lang (Pierce Brosnan from “Mamma Mia!”).

Although he may have needed the money, it’s an assignment our hero probably should have passed on.

After all, he’s replacing another writer whose body mysteriously washed up on the shore near Lang’s vacation home in Massachusetts.

Plus, Lang has been accused of war crimes by another British government official. It seems that Lang may have turned over some terrorism suspects to the CIA who, in turn, reportedly tortured them.

The timing for an uplifting memoir seems ill advised and soon, the Martha’s Vineyard area is teeming with media and anti-war protesters.

But worse, our clueless writer stumbles upon some troubling evidence that his predecessor inadvertently uncovered. Could Lang have been a longtime collaborator with US interests? Indeed, could he have actually been a card-carrying CIA agent?

The screenplay by Polanski and Harris builds a considerable degree of tension as our hapless hero slowly puts the pieces together.

McGregor (who reportedly replaced Nicholas Cage on this project) ably evokes the character’s naiveté. There are moments, however, when his behavior seems questionable for a seasoned, worldly writer.

Polanski has populated his acting ensemble with solid pros.

Olivia Williams (“An Education”) plays Lang’s long-suffering wife, Ruth. She stands by her man even though it’s obvious that he’s carrying on an affair with his aide, Amelia (Kim Cattrall from “Sex and the City.”)

Other notable supporting players include Tom Wilkinson, Timothy Hutton and James Belushi. Even 94-year-old Eli Wallach shows up as a Martha’s Vineyard resident who has noticed some strange events since Lang’s arrival.

Although is has some irritatingly awkward moments, “The Ghost Writer” is a pleasingly suspenseful addition to Polanski’s eclectic oeuvre. (R) Rating: ***1/2

* Avoid at all costs
** Only if you're bored
*** Good movie
**** Well worth your time
***** Be sure to see it