SAHARA BY PETER KEOUGH

To judge from the five-minute opening sequence, Sahara might have been made by someone with intelligence and talent. A superior History Channel–type episode about a Confederate ironclad running a Union blockade fades into an engraving of the vessel lying among the items in the living quarters of that 21st-century Indiana Jones, Dirk Pitt (Matthew McConaughey). The newspaper clippings, snapshots, and assorted gewgaws fill in the back story and set the stage for the adventure to come. Not just a splendid bit of exposition, but a sly look at cinematic semiotics and layers of signification . . .

Then I woke up and the film directed by Michael Eisner’s son Breck started, an astoundingly dumb, noisy, inept adaptation of the Clive Cussler bestseller. Any film that poses McConaughey and Penélope Cruz, who plays a doctor tracking down the source of a mysterious West African plague, as a romantic item is doomed to begin with, but their lack of heat is almost a relief from the kinetic futility surrounding them. Pitt’s search for the vessel of the opening takes him up the Niger River, which happens to be along the good doctor’s way, and together and separately they encounter many preposterous special effects and narrow escapes that we’ll all be able to share when the video game comes out. At the Apple Valley, Entertainment, Flagship, Holidau, Providence Place 16, Showcase, and Tri-Boro cinemas. (127 minutes)