Opens: Friday, Aug. 22 (Roadside Attractions)

Just when you thought documentaries had effectively run out of subjects chronicling the various ways in which our country has messed up, along comes "I.O.U.S.A" to draw attention to yet another inconvenient truth.

But this smartly assembled wake-up call concerning the nation's lousy spending habits proves to be as unexpectedly spirited as it is dispiriting.

Updated from the version screened this year at Sundance, the eye-opening film should be able to overcome potential audience reluctance by capitalizing on good word-of-mouth.

Directed by Patrick Creadon, who put an energetic spin on the New York Times crossword puzzle in his 2006 film "Wordplay," the new documentary takes its cue from the book "Empire of Debt," by Addison Wiggin and William Bonner, and clocks in at a tight 90 minutes.

Creadon successfully overlays a relatable human face against the inevitable barrage of facts and red-inked figures in the form of Dave Walker, the former U.S. comptroller general, who, along with Concord Coalition executive director, travels the country, town crier-style, on a Fiscal Wake Up Tour.

Walker, whose voice-over ominously kicks things off with the contention that "the most serious threat to the United States is not someone hiding in a cave in Afghanistan or Pakistan but our own fiscal irresponsibility," helps to make the economics primer surprisingly accessible, as do those colorful graphics and lively film and TV clips.

Also on hand to help explain the trajectory of a federal debt that has escalated to more than $9.6 trillion and ticking are former Federal Reserve chairman Alan Greenspan, former Treasury Secretaries Paul O'Neill and Robert Rubin and fiscally responsible billionaire Warren Buffett, all of whom believe there might still be a bit of light at the end of this gloomy tunnel.

Production: Open Sky Entertainment. Director: Patrick Creadon. Writers: Patrick Creadon, Christine O'Malley, Addison Wiggin. Producers: Christine O'Malley, Sarah Gibson. Executive producers: Addison Wiggin. Director of photography: Patrick Creadon. Music: Peter Golub. Editor: Doug Blush. Rated PG , 90 minutes.