The time is 8:30 a.m. The place is Dulles International Airport. The high-ceilinged terminal is nearly empty, but Downstairs at International Arrivals, business is about to pick up.

A growing knot of people waits impatiently for friends and relatives, due any minute now on Braniff's Flight 974 nonstop from Lima, Peru. They stretch their necks whenever a set of pneumatic double doors marked No Admittance whooshes open.

Beyond those doors lie U.S. Customs, and a dozen more people -- some of them armed federal drug agents -- equally eager to see who and what is aboard Flight 974. The weekly, Friday morning flight from South America has a nickname among law enforcement officers at Dulles: The Cocaine Express.

The Braniff DC8 touches down at 8:58, 28 minutes late on its 6 1/2-hour journey. While mobile lounges carry the 157 weary passengers and nine crew members toward the terminal, a uniformed Customs agent already is charging aboard the plane with "Jaws," a large, black dog trained to sniff out illegal drugs.

The cat-and-mouse game of find-the-smuggler is on.

The flight -- the only nonstop from South America to Dulles -- is a main connection between Peru, one of the world's major sources of cocaine, and Washington, one of several East Coast cities with a rich and ready market for the drug.

"It's a 'hot' flight," says William J. Logay, the Drug Enforcement Administration special agent in charge of DEA operations at Dulles.

A Braniff spokesman acknowledges the drug problem, saying arrests at Dulles, 16 of them involving incoming Braniff passengers. Customs estimates the street value of drugs seized in those 16 arrests at $17.6 million, a spokesman says.

Drug law enforcement agents acknowledge Washington-bound cocaine largely travels a land route up the East Coast from Florida. But they say the relatively quick, effortless air trip allows distributors to lure many passengers into becoming "mules," or drug couriers, usually on a one-time basis in return for $1,000 to $2,000 in supposedly easy money.

Law enforcement officials watching Dulles say the smuggler's journey most often ends not in freedom here on in New York -- where the Braniff flight continues from Dulles -- but in U.S. magistrate's court in Alexandria. The charges, brought by the U.S. attorney's office, are smuggling and possession with intent to distribute.

Three men arrested at Dulles last month on two successive Fridays were indicted this week by a federal grand jury in Alexandria and now face maximum 15 year sentences if convicted. All three were aboard Flight 974.

If the battle of wits between smuggler and authorities is intense, the maneuvering itself is surprisingly subtle, carried out discreetly enough that most passengers appear unaware of the struggle in their midst as they trudge through Customs lines.

While passengers' passports are checked and their luggage searched, Jaws or a second dog is aboard the plan, sniffing the aisles and seats for what in Customs jargon is called a "dead scent alarm" -- evidence that drugs were recently present.

Inside the terminal, uniformed Customs officers open bags, prod packages and ask the stream of seemingly routine questions that overseas travelers have come to expect.

"There's no Fourth Amendment here," says Logay. Submitting to a search is not optional for international passengers crossing the border.

One traveler in his 20s, dressed in jeans and lugging a half-dozen canvas knapsacks, nervously rubs his lips with a hand and immediately draws a penetrating, 20-second stare from uniformed Customs supervisor Bill Morgan. The youth makes it through, however.

New York City businessman Hugh Henderson, in gray suit and white shirt without a tie, is 20 minutes getting past the baggage inspection, where even a souvenir boa constrictor skin is carefully unrolled before receiving clearance.

Agents say inventiveness is the mark of the successful smuggler. Pat Solan, chief Customs inspector in the Washington area, recalls an overseas passenger who carried a bowling ball through the line. Sliced open with a power saw, she says, the ball revealed a cache of cocaine.

There is often cocaine taped to the waist, to the thighs or stashed in body cavities, the agents say. On this day, nearly a dozen passengers are silently escorted into a small side room for a "pat down," a superficial body search. There are strip searches if officials believe it is warranted.

By 10:15 a.m., only a handful of passengers remains in line. One of them is a heavy-set man with thinning blond hair who is chewing gum furiously and shifting form one line to the next.

"He was the first one off the plane," special DEA agent Bob McCracken says quietly, "and now he's last in line."

Ten minutes later, as the man clears the baggage inspection, a plainclothes Customs agent discreetly takes the man by the elbow, shows his badge and walks him into the little room. McCracken waits outside with the luggage.

A few moments pass before the man reemerges, reclaims his suitcase and walks through the pneumatic doors into the terminal, free to go.

One of McCracken's colleagues walks by shaking his head. "He was sweating in there like he was carrying a couple of kilos," says the agent.

Now the inspections quickly wind down. The Cocaine Express apparently is clean this week -- or the mouse has successfully escaped the cat.

"If I were Customs, I'd search my bags a lot more carefully," says one passenger, Linda Berho, 21, of Chevy Chase. "There's a million places they don't look."