After showcasing the mousy crossword puzzle in his engaging first documentary, "Wordplay," Patrick Creadon turns to a topic that makes the Sunday acrostic look like a certifiable movie star: "I.O.U.S.A." tackles the endlessly alluring matter of the national debt.

Packed with facts, figures and the testimony of policy experts, the film is no wallow in wonkiness, though, but a surprisingly sprightly tough-love lesson in fiscal responsibility. For anyone seeking a clearer understanding of the financial state of the union¿and strong enough to take the sobering news¿Creadon's film is a good place to start. It's heartening, too, to know that it will screen at the upcoming conventions of both major parties.

Alarming though it is, the film never loses a crucial sense of humor. Using crisp charts, new interviews and archival footage that includes Bing Crosby crooning for war bonds, Creadon sounds an urgent call for political accountability and citizen involvement. Without addressing the proposals of presidential candidates John McCain and Barack Obama, the documentary makes clear that until politicians get real about remedying budget and trade deficits, the nation is on precarious ground.

At the center of the primer are two likable protagonists, former Comptroller General David Walker and the Concord Coalition's Robert Bixby , who travel the country on their nonpartisan Fiscal Wake-up Tour. "I.O.U.S.A." couldn't be more timely; if the catastrophic storm it warns of hasn't yet struck, Americans are already well into a rainy day.