It's a warm, overcast Saturday morning at a flea market in central New Jersey. Through the mist, I can make out acres of vendors setting up their stands outdoors. By 9 a.m., folding tables are filled — iPhone screens, Gatorade, raw honey — and shoppers are streaming in.

A quarter mile down the road, a group of guys is hanging out behind a deli. They’re brawny, wearing Harley-Davidson T-shirts, cargo shorts, jeans. They wouldn’t be out of place playing pool at a dive bar or tailgating at a Giants game. They’re regular guys.

Except that they’re anything but.

Between them, these five plainclothes cops have eight decades of experience in gangs, terrorism, narcotics, human trafficking, organized crime, and cargo theft. They’ve seen the worst and darkest corners of humanity.

Today, they’re here for makeup.

“Jim, do we know where the product is coming from?” This is Lieutenant Daniel Bergin, the leader of the New Jersey State Police Interstate Theft North unit. With a shaved head and wearing a Dropkick Murphys T-shirt, Bergin speaks bluntly as the team waits for their egg sandwiches. “China. It’s always from China,” says Jim Ricaurte, the private investigator who’s been canvassing this area for months.

The “it,” in this case, is M.A.C. makeup — presumably fake. Within the hour, these officers will begin staking out a vendor at the flea market. Ricaurte, who owns a company called Allegiance Protection Group, works closely with the Estée Lauder Companies. You read that right. In 2008, when they saw an increase in counterfeit products, the Estée Lauder Companies, which own M.A.C., created an anti-counterfeiting unit — 24 people whose sole job it is to seek out counterfeit beauty products. Because of the simple, and iconic, packaging, M.A.C. products are a frequent target for counterfeiters.

A former detective, Ricaurte spends a fair amount of his time searching markets like this one for counterfeit goods — makeup, handbags, consumer electronics, alcohol. Whenever he sees M.A.C., his antenna goes up.

“She’s got a lot of stuff,” Ricaurte says, referring to the focus of today’s operation. Her shop has prime real estate in the indoor section of the flea market and looks more like a store in a strip mall than a flea market table. Several of the men on site today will purchase M.A.C. items from the store and ferry them back to the parking lot, where a woman named Nancy Gordon sits in an unmarked van. Gordon is the manager of global trademark protection for the Estée Lauder Companies. She’ll test the products to try to verify what everyone already suspects: They’re fakes.