On the afternoon of May 16, 2007, an Ilyushin Il-76 cargo plane rumbled down the tarmac at Burgas Airport in eastern Bulgaria, its hold packed with 110,000 grenades bound for Kabul, Afghanistan. The aircraft lifted off, climbed above the rolling farmlands to the west and the Black Sea to the east, and headed toward war.

Half a world away, on the first floor of a sun-dappled office building amid the palm trees of Miami Beach, Florida, a 21-year-old high-school dropout named Efraim Diveroli paced nervously. He was the president of AEY, Inc., a licensed arms dealer, and those were his grenades. The flight contained the first in a series of shipments his company had agreed to make on behalf of the U.S. Defense Department to supply the Afghan army and police force with hundreds of millions of rounds of ammunition. All told, AEY's contract was worth almost $300 million, and the company was late on delivery. Officials from the U.S. Army were calling to find out when the ammo would move. At 10:30 a.m., AEY's 25-year-old vice president, David Packouz, sent an e-mail to Pentagon contacts informing them of the plane's departure. But even with the Ilyushin aloft, no one was ready to celebrate. A lot could go wrong with a plane full of explosives flying into a war zone.

It wasn't until about midnight that the Ilyushin landed and a U.S. Army major in Kabul signed the shipment's certificate of conformance. By then AEY's staff had gathered in Diveroli's 28th-floor apartment in South Beach's Flamingo building. Diveroli uncorked a bottle of champagne. Touchdown in Kabul meant that AEY was poised to become a major player in the global arms market, making Diveroli a very wealthy man. Overnight, the tiny business he had launched in 2004 at the unlikely age of 18 had become the main supplier of munitions to the government of Afghanistan.

Five days later AEY's next shipment, of 7.62 mm AK-47 cartridges, took off from Rinas, Albania, and again champagne flowed. But this celebration was premature. By the time the cargo touched down, Diveroli was marked for ruin. He would become a symbol of a mismanaged war effort and the target of an embarrassed, vengeful Washington. And before it was all over, an AEY business partner turned whistle-blower would wind up dead on a deserted road in the middle of nowhere.

Efraim Diveroli was a chubby, hyperactive 16-year-old living in an Orthodox Jewish enclave of Miami Beach when he got his first gun, a Ruger .22 caliber rifle. But he had already developed what his grandfather Angelo Diveroli describes as a passion for firearms. "Ever since he was a little boy, I would take him to gun shows and he could identify every model of gun," Angelo recalls. "He's a genius."

In school Diveroli rarely displayed the same focus. At 17 he was kicked out of Hebrew academy for smoking pot. His Orthodox father, Michael Diveroli, who ran various small businesses, was furious. Efraim moved to Los Angeles to take a job with his uncle, who owned a law-enforcement-supply company. It was there, equipping police departments, that Diveroli learned how to bid on government contracts. It was also there that he met Ralph Merrill, a Vietnam vet who knew his way around the international arms market, buying and selling weapons in places like Israel, South Africa, and Croatia. Diveroli absorbed everything he could, and Merrill quickly noticed what he described in a letter as his young friend's "innovative thinking and absolute mission dedication." On his MySpace page, Diveroli later explained this period: "I had problems in high school so i was forced to work most of my teen years," he wrote, "and i probably grew up way to [sic] fast."