Whenever the French excrete one of their usually crummy little thrillers, usually starring the same troupe of actors, the alleged critics invariably invoke the sacred name of Alfred Hitchcock, an auteur they admire even more than the sainted Jerry Lewis. Although one or another French flick might include a modicum of mystery and a soupçon of suspense, most of them resemble a Hitchcock picture about as closely as Jean Paul Sartre resembles Clint Eastwood. In fact, his imitators on both sides of the Atlantic, including his most devoted and accomplished disciple, Brian De Palma, tend to concentrate on Hitch's dark side, missing entirely his light touch, the characteristic treatment of perfectly serious material with a comic sensibility.

Because of their audience, few summer blockbusters attempt the Hitchcockian manner, but beneath its predictable surface of spectacular chases, stunts, gunfights, and explosions, "Knight and Day" demonstrates a surprising fidelity to the lessons of the master. The film takes its inspiration not from the neurotic, haunted explorations of guilt and obsession, like "Shadow of a Doubt," "Vertigo," or "Psycho," but from such witty mixtures of fun and danger as "The 39 Steps," "North by Northwest," or "To Catch a Thief." It includes such classic Hitchcock elements as an innocent but sexy blonde, violent action on a train, exotic locales, and even a true McGuffin.

In the thriller tradition, the movie opens with an apparently random event that draws a perfectly innocent person into a complicated and dangerous plot. June Havens (Cameron Diaz) accidentally collides with a fellow passenger, Roy Miller (Tom Cruise), in the Wichita airport. On their flight to Boston, Miller charms her with a smooth line of patter, but when she retreats to the restroom to make herself more attractive, Miller calmly faces and thwarts a concerted attack from the few passengers on board and the whole crew, then lands the plane himself.

From that moment on, the picture falls into a reiterated pattern of ferocious battles, remarkable chases, and comical reactions. Miller tells June that he is the target of a group of rogue CIA agents colluding with an international arms dealer, who will try anything to steal a new invention from him, a small battery that can power an entire city. That problem generates a ridiculous variety of gunfights and a series of pursuits and flights by automobile, motorcycle, airplane, helicopter, bus, and that Hitchcock favorite, a railroad train, in this case the Orient Express.

The action takes place against the background of such photogenic locations as Miller's remote tropical island, a grand hotel in Salzburg, a mansion in Seville, and half the highways of Europe. In the process of all that travel, scores of people attempt to kill both Roy and June, thousands of bullets spray all over the screen, and dozens of vehicles overturn, cartwheel, collide, and explode. Along the way, a great many characters, innocent and otherwise, suffer violent, even bloody death, but the movie never pauses to allow any emotional reactions beyond June's constant and essentially comical astonishment at all the peril and all the narrow escapes.

Throughout "Knight and Day" Miller accompanies his amazing ability in just about every endeavor, from hand-to-hand combat to marksmanship to jumping from car to car during a frantic high-speed chase, with a running commentary on June's behavior. While hanging upside down over the windshield of a speeding car that she tries to control from the back seat, and firing his weapons at the pursuers, he compliments the frightened, screaming woman on her driving skills.

That behavior, accompanied by Cruise's constant winning smile and a slightly nutty gleam in his eyes, maintains the movie's light tone throughout its most violent sequences, so that all the shooting, exploding, and killing never really seem important, shocking, or anything but good clean fun. In keeping with a significant thriller theme, the picture also actually focuses on Cameron Diaz's character, the real protagonist, who finds in herself a resourcefulness to match both Cruise and her adversaries. Diaz and Cruise, who worked together in the weird "Vanilla Sky," make a fine pair in "Knight and Day," handsome, lively, and entirely entertaining. Hitchcock would love them.