Monumentally silly yet occasionally rousing, "Sahara" blows into movie theaters on the strength of the appeal of Matthew McConaughey.

McConaughey first impressed movie audiences playing a Texas slacker in the 1993 cult comedy "Dazed and Confused." He now seeks to widen his audience playing Dirk Pitt, a lucky and resourceful action hero with pretensions to be the American version of James Bond.

Those unfamiliar with the source material are going to have a much better time as Pitt takes on a ruthless African dictator and a greedy French billionaire who are responsible for launching a lethal red tide of toxic waste, which causes decay, dementia and cannibalism.

Those captivated by the 18 Dirk Pitt adventure novels penned by Clive Cussler are not likely to embrace McConaughey as the new face of the daring and courageous Special Projects Director for N.U.M.A, the National Underwater and Marine Agency.

There is likely to be an even greater outcry at the casting of Steve Zahn as Pitt's burly sidekick and childhood friend Al Giordino, who has now been essentially reduced to comic relief.

Together these amiable actors possess a certain scrappy screen chemistry in which humor and sarcasm are pivotal but they both are about a decade younger than the characters as written in the novel.

Fans of the books however should be happy with William H. Macy as Admiral James Sandecker, the dapper head of N. U. M. A., which in this movie is now a private company and not an agency of the U.S. government.

The source novel, which was published in 1992, is only the second Pitt adventure to be filmed since the character was created in 1965. Cussler hit the literary jackpot in 1976 when the fourth Pitt novel "Raise the Titanic" became a bestseller. A disastrous film version that Cussler reviled arrived in theaters four years later and featured Richard Jordan as Pitt, M. Emmet Walsh as Giordino and Jason Robards Jr. as Admiral Sandecker.

Cussler is currently involved in a breech-of–contract lawsuit against the makers of "Sahara," claiming they made the current film for which he allegedly had script control after he rejected several submitted screenplays.

Truth be told, there are four credited screenwriters on "Sahara," and they have not only tightened up the story found in the 11^th Dirk Pitt novel but are also responsible for some rather constructive changes.

The historical back-story in "Sahara," which opens the film, still revolves around the disappearance of the Texas, a Confederate ironclad naval vessel last seen in April, 1865 off the coast of Virginia, loaded with gold. Fans of the book are going to be mighty steamed by the fact that Cussler’s bold subplot, which involved the kidnapping of President Abraham Lincoln, has been totally jettisoned.

Of course, one major question the movie never addresses is exactly why representatives of a defeated government that fought to support the institution of slavery would ever think that Africa would make a good place to hide out.

Jump ahead to the present day as Pitt fortuitously prevents of the murder of Dr. Eva Rojas, a dedicated member of a World Health Organization medical team played with adequate pluck by Penelope Cruz.

It seems that her confirmation of a possible outbreak of plague in Mali would be bad for business for those who operate a toxic waste disposal planet located in the middle of the Western Sahara. Lambert Wilson, who underplays the greedy Massarde, has the odd distinction of having also co-starred as a villain in a critically disdained 1983 release of the same name which starred Brooke Shields.

McConaughey and Cruz, who are currently dating, got acquainted during the filming of the current "Sahara" but the on-screen love story between their characters takes a back-seat to increasing body counts and making wisecracks under pressure.

Under the keep-it-moving direction of Breck Eisner, "Sahara" provides audiences with plenty of action and explosions and reckless derring-do. Filmed mostly in Morocco, the first major motion picture directed by the son of Disney mogul Michael Eisner offers exotic scenic vistas and macho hi-jinks, but those looking for credibility are better off at a different movie.