Jack Nicholson must have signed on to “About Schmidt” knowing it would be seen as the bookend to “Five Easy Pieces.”

That 1970 film was a road movie in which Nicholson played an angry young man who refuses to take his place in society. “About Schmidt” is a road movie in which Nicholson plays a befuddled old man who loses his place in society and wonders how to create another, if it’s not too late.

The story opens with Warren Schmidt (Nicholson) sitting in his barren office, impassively watching as the clock ticks toward 5 p.m. on the last working day of his life. As when the second hand reaches the 12, Warren gets up and calmly walks out of the metaphorically named Woodmen of the World Insurance Agency.

Shortly into his retirement his wife (June Squibb) dies. Robbed of the things that defined his identity for the last 42 years – his career and his marriage – Warren Schmidt no longer knows who he is.

All he knows is that his daughter, Jeannie (Hope Davis), is about to marry a moron. The groom, Randall (Dermot Mulroney), is a waterbed salesman defined by his hairstyle, a mullet of course.

Taking the wheel of the monstrous Winnebago his wife talked him into buying, Warren drives from Omaha to Denver determined to stop the wedding. Along the way he hopes to rediscover himself.

As Gene Hackman did a year ago with Wes Anderson and Owen Wilson in “The Royal Tenenbaums,” Nicholson does with Alexander Payne and Jim Taylor – an acting veteran of the last great age of American cinema partners with a rising pair of collaborators. Director Payne and his writing partner Wilson created the satires “Citizen Ruth” and “Election,” which ranks with Anderson and Wilson’s “Rushmore” as one of the stellar breakthrough films of the 1990s.

“About Schmidt” is a satire also, but a gentler one that doesn’t disdain its characters. Warren Schmidt’s tragedy is that his career and marriage sucked away his emotion. He became an automaton decades ago without realizing it.

Long-repressed feelings burst through the most unlikely conduit: Warren’s letters to the African child he decided to sponsor after watching a late-night commercial. The words “Dear Ndugu” signal weird and wonderful confessions will spill forth.

Though his character is emotionally comatose, Nicholson comes alive with his freshest, least mannered performance in decades (though his trademark smirky persona also was absent from his last appearance in “The Pledge”). With a slack expression and wispy hair, Nicholson’s Schmidt looks like a lost cause even before drained of his identity.

When Warren arrives in Denver, things turn more bizarre and darkly comic. He discovers that his daughter’s future in-laws (Kathy Bates and Howard Hesseman) are former hippies who still believe in free love. And Bates’ character dotes on her underachieving son.

The mood turns so grim that the only thing false is the ending. Trying their hand at hope, Payne and Taylor reveal they should stick to cynicism. But Nicholson’s performance is powerful enough to shade this artificial sunshine.