It’s easy to forget that Roman Polanski can be awfully funny. He’s directed outright comedy in the past, and his career best work in Chinatown and Rosemary’s Baby is shot through with humor — it’s hard not to laugh at the director as he plays a diminutive Napoleonic thug, or at Ruth Gordon’s doddering, meddlesome neighbor. But his more recent work has been more rigidly serious, underseen, or just plain awful to appreciate or have room for that humor.

With The Ghost Writer, the director not only does his most assured thriller filmmaking since the mid-1990s, he also does some of his wittiest work in years. Ghost Writer is quintessentially Polanskian, with the director once again returning to his favored story architecture of a solitary protagonist far out of his or her depth amid supporting characters with secret agendas. And that trademark humor is back, often to obscure characters’ sinister intentions — certainly the case with his own cameo in Chinatown, or Gordon’s satan-worshipping octogenarian in Rosemary — or just window dressing to mask Polanski’s own darker storytelling motives.

The lost hero here is the titular ghost writer (Ewan McGregor), unnamed in the movie as he is in Robert Harris’ novel, and often simply referred to as the Ghost. He’s offered the task of cleaning up the autobiography of former British Prime Minister Adam Lang (Pierce Brosnan), after Lang’s first ghost writer falls over the side of a ferry and drowns on the way to the secluded New England island community — also unnamed, but likely meant to be something like Martha’s Vineyard — where Lang has a compound. The Ghost claims to have no interest in political bios, but a huge advance offered by a gruff publishing executive (amusingly played by Jim Belushi) is enough to bring him on board, even if he must practically do a complete re-write in four weeks.