Over the past couple of years, Sean Penn has been acing the roles of anguished men—from a college professor dying of heart failure in 21 Grams, to an angry, grieving father who has just lost his daughter in Mystic River—a portrayal that won him an Oscar for Best Actor last year. Now, in first-time director Niels Mueller’s The Assassination of Richard Nixon, Penn plays another tormented soul: Sam Bicke, a disturbed loner who attempted to assassinate the President in 1974.

THE ASSINATION OF RICHARD NIXON ( * * * )
Directed by Niels Mueller.
Starring Sean Penn, Don Cheadle and Naomi Watts.
(Rated R, 95 mins.) At the Osio Cinemas.

The film begins in 1974, as Bicke prepares to enter the Baltimore airport with a handgun. Then the movie hops back about a year so that we can watch Penn’s office furniture salesman startto unravel.

In the first part of the movie, Penn oozes awkwardness as a horrible salesman and pitiful man trying to mend relations with his ex-wife, an exasperated cocktail waitress played by Naomi Watts. In the meantime, Bicke’s one real hope is to start a tire business with his only true friend, Bonny—played very low-key by Don Cheadle.

As the film progresses and Bicke’s mental condition deteriorates, the loner starts to identify with militant outsiders like the Black Panthers and resent people like President Nixon, who his boss calls “the world’s greatest salesman.” Nixon, who Bicke watches on television on and off through the whole movie, almost deserves an acting credit for a supporting role, as he goes from being re-elected for a second term to getting grilled after the Watergate scandal breaks.

Despite Penn’s stellar performance, The Assassination of Richard Nixon is a good but not great movie. For one, the script never adequately explains why Bicke is damaged goods at the beginning of the film. In addition, the viewer can easily predict Bicke’s decline—losing his job, becoming further estranged from his family—from the movie’s first few scenes. (Maybe that’s one inherent problem with basing a film on atrue story.)

With its predictable script and a few unintentionally humorous moments—including Bicke’s unhealthy attachment to having a mustache—The Assassination of Richard Nixon’s dark subject matter would also be unbearable in the hands of a lesser actor than Penn. Despite being backed by exceptional actors like Cheadle and Watts, Penn, who is onscreen in virtually every scene of the movie, is really the only reason to watch.

As Penn runs through every dramatic device in the book—fierce rants, sobbing and facial tics—to show Bicke’s deteriorating mental health, he creates a character that can stand comfortably next to film’s biggest nutjobs—an esteemed crowd that includes misfits like Robert De Niro’s Travis Bickle and Dustin Hoffman’s Ratso Rizzo.