Starring Greg Kinnear, Lauren Graham, and Alan Alda. Rated PG.

If you're old enough to remember when windshield wipers were unable to pause during a slight drizzle, you'll never forget the annoying squeal of rubber dragging across dry glass. Thanks to engineering professor Bob Kearns, that irritating sound no longer exists. In the '60s, the Detroit-based Kearns invented the intermittent windshield wiper.

Although Flash of Genius delights in telling the story of that discovery, it gets bogged down in the protracted legal battle that Kearns launches after the Ford Motor Company steals his idea.

Based on the New Yorker article by John Seabrook, the screenplay takes great pains to show us just how far one man will go for the sake of principle. As Kearns, Greg Kinnear endows his geeky character with a sense of decency that's as noble as it is frightening.

Despite a nervous breakdown, Kearns refuses to compromise. Explaining his growing obsession to have Ford publicly admit its guilt, he tells a friend: “They may be just windshield wipers to you, but to me they're the Mona Lisa.”

We watch as the increasingly fragile Kearns sacrifices his job and his family to his compulsion for justice. Eventually, Ford starts throwing big money at Kearns in a futile attempt to settle.

Although director Marc Abraham does his best to make the underdog inventor look like a dashboard version of Rocky Balboa, we can't help but sympathize with the maddening frustration of his wife (Lauren Graham) and lawyer (Alan Alda).

Relentless conviction has its place. But at a running time of two hours, Flash of Genius starts to wear thinner than a junkyard wiper blade. And, believe me, we see plenty of wiper blades. About two-thirds of the way through, they take on the numbing beat of a metronome counting off each passing minute.