Sahara

When an author launches a nearly $100 million lawsuit against a movie based on his novel, that can be a bad sign. When four separate writers are credited with a screenplay (five, if you count Clive Cussler, author of said novel-although he'd probably prefer that you didn't), that too can be a bad sign.

Sahara arrives in theaters with just such a pedigree. Rated a mild PG-13 (for action violence) and centering on a treasure hunter obsessed with an arcane historical mystery, it's easy to compare Sahara to last year's surprisingly successful National Treasure. But where National Treasure held to a certain silly logic and narrative structure, Sahara becomes increasingly unhinged as the story progresses.

Sahara actually starts out promisingly, opening with a flashback to the final days of the Civil War. The Confederate ironclad Texas is under heavy Union attack. In the dead of night, it steams out of port, loaded with some mysterious cargo-and appears to escape. Flash forward to modern-day Africa. Dirk Pitt (Matthew McConaughey) is a member of the National Underwater Marine Agency (NUMA) crew in search of ancient artifacts buried in the ocean.

After completing his current mission, Pitt asks crew commander Admiral Sandecker (William H. Macy) for permission to head up the Niger River in search of the Texas-clearly a life-long obsession. He's accompanied by NUMA colleague/long-time buddy/comic-relief Steve Zahn. In tow is World Health Organization doctor Eva Rojas (Penelope Cruz).

So far so good. Rojas is after the source of an epidemic she's just uncovered, while Pitt has three days to find some sign that his phantom ironclad actually did make the unlikely journey across the Atlantic to Africa. The voyage up the Niger ends in a well-staged boat battle, and the movie is cruising along nicely as a mindlessly entertaining Allan Quatermain/Indiana Jones derivation.

It's tempting to think that just one of the writers was responsible for the script up to this point, because then a series of barely connected action sequences and plot devices completely derails the picture. By the time the trio discovers a plot involving a ruthless dictator, a French industrialist, and toxic waste, the mystery of the Texas has become little more than an afterthought.

Sahara benefits from a clean script (largely bloodless violence, little bad language, no sex), promising characters, and an intriguing setup. One wonders what could have resulted from fewer cooks in the kitchen.