"Diamonds" is a movie I feel guilty for panning because at its heart are the best of intentions and a pair of legendary actors.

A cliché-per-mile road movie with all the standard-issue accouterments (classic convertible, bonding between estranged relatives, a gambling stop in Nevada), the picture's main selling point is a snappy performance by Kirk Douglas, playing a grandfather who, like the actor himself, is recovering from a stroke.

The joy Douglas gets out of being back at work comes across in his character, a former welterweight champ determined not to be slowed down by his impediment, which manifests itself mostly in diminished motor skills and slightly slurred speech.

But save for Douglas, who took this role for two good reasons (he wanted to prove something to himself and it happened to fit his circumstances), there isn't a soul associated with this movie who shouldn't be embarrassed by it.

The plot revolves around Douglas leading his milksop son (Dan Aykroyd) and teenage grandson (Corbin Allred, "Anywhere But Here") to Reno on a treasure hunt for a hidden package of diamonds owed him by a fight promoter for 40 years.

Along the way, they encounter opportunities to mend fences and make new connections at clockwork-like intervals. Gramps gives his boxing robe to the unrealistically wide-eyed, Wesley Crusher-like teen. Aykroyd whines, "All I ever wanted from you is that you believe in me a little!" They hit the casinos and win. Then Granddad and grandson conspire to drag bitterly-divorced dad on a character-building (?!?) trip to the local brothel, staffed by only-in-the-movies, intelligent, well-adjusted hookers.

The movie stalls out for almost an entire reel during this set piece, while Douglas has a heart-to-heart with the madam (Lauren Bacall), Aykroyd loosens up by getting tied up, and Allred gets his cherry popped by a compassionate Jenny McCarthy after a couple, um, misfires. It's difficult to say (and painful to think about) which of these episodes is the most embarrassing.

Then the quest for the diamonds resumes, the stones becoming one of the most ridiculously flagrant metaphors in recent movie memory (Douglas even calls them "magic diamonds").

Directed by a TV bit player named John Asher and written (apparently with a straight face) by first-time screenwriter Allan Aaron Katz, "Diamonds" opens with mock newsreel footage from Doulgas' boxing heyday (footage from his 1949 film "Champion" is used), signaling the movie's intent as an all-American feel-good flick.

Until I saw "October Sky" last year, I thought that genre was even deader than the road trip movie. But while the genre may still have some life in it, the only thing giving this cheaply sentimental picture of completely generic conflicts any kind of pulse is the trite soundtrack of lamenting strings and triumphantly crashing cymbals.