The new political thriller “The Sentinel” is a taut, twisty, and gloriously improbable flick. It won’t win any Oscars, but this cross between “In the Line of Fire” and “The Fugitive” will entertain a grown-up crowd.

The star-studded cast is led by Michael Douglas, who plays secret agent Pete Garrison. Wrongly accused of plotting to assassinate the president, Garrison also happens to be fooling around with the first lady, played by Kim Basinger.

“The Sentinel” opens with an inside peek at how the presidential bodyguards safely shuttle their charge to and fro. It’s a bit of a commercial for the Secret Service, who in their suits and sunglasses happen to be the most fashionable law enforcement guys around.

All glamour aside, an affair with the first lady is asking for trouble. Unjustly framed for attempted assassination, the disgraced Garrison has to go on the run – as he’s the only person who can possibly foil the conspiracy. Ratcheting up the tension, Garrison is pursued by a former protege with a personal ax to grind played by Kiefer Sutherland. The Javert-like precision Mr. Sutherland’s character employs to hunt his wily prey supplies the most exciting parts of the movie; the two male leads have terrific chemistry.

Like “The Fugitive,” it’s exciting to see a hero use his wits as the net closes in. “The Sentinel” is the sort of movie that allows the viewer to ask: “What would I do in this situation?” Mr. Douglas’s character knows how to hack into phone lines, kill terrorists, and sneak into Canada even though he’s the most hunted fugitive in the government.The layman might not get as far.

As the first lady, Ms. Basinger is radiant and alluring. Though her appeal seems to defy age, there’s a moment when she and Mr. Douglas are in a heavy-breathing lip-lock in which his age is more noticeable.

But the fact that, at age 62, he can still be a credible romantic lead is a testament to the aging baby boomers’ determination to maintain their vitality. Mr. Douglas growls, runs, shoots, and loves with all the haggard intensity that made him a star decades ago.

“The Sentinel” is an excellent vehicle for Mr. Douglas, who’s made a career playing flawed, morally compromised yuppies.Who else has the knack for making Wall Street sharks, adulterers, and sex-crazed cops seem charismatic and sympathetic?

Though “The Sentinel” may be a popcorn flick, there’s a lot to enjoy here. One of the more unexpected bonuses is Eva Longoria, who gives an understated performance that doesn’t exploit her celebrated beauty. The sharp, urgent script by Gerald Petievich helps things considerably. “The Sentinel” moves along like an action-movie version of “The West Wing” – minus the hackneyed liberal bellyaching. In fact, curiously enough, “The Sentinel” is as apolitical as a political thriller can get. What a relief.