Fifteen shots felled the elephant. It was a few weeks into Congo's springtime rainy season, and the animal, an adult male, collapsed among dense green stalks of yard-high grass. A few miles away, Dieudonné Kanisa, a compact and muscular Congolese ranger, heard the shots as he patrolled the northern bank of the meandering Garamba River, looking for poachers. With his four fellow rangers beside him, Kanisa moved toward the gunfire.

Back at headquarters, the manager of Garamba National Park, Erik Mararv, grabbed his rifle and headed for the park's helicopter with pilot Frank Molteno, a South African with a lifetime's experience flying all kinds of aircraft, often in places without runways or rules. Mararv, a lean 32-year-old Central African–born Swede, oversaw the rangers tasked with protecting Garamba, a park the size of Delaware in northeastern Democratic Republic of Congo. The 80-year-old World Heritage Site is an immense stretch of savannah and woodland in the heart of Africa, a gently undulating landscape of nine-foot-tall elephant grass and scattered sausage trees, interrupted by swamps and pocked with the scars of abandoned termite hills. It is also home to one of the largest, most threatened populations of elephants in central Africa. In the past three years, 13 rangers have been killed in 56 shoot-outs with poachers. The corresponding elephant death toll in that time: 256.

Every rifle shot in Garamba sets off a dangerous race to find the carcass before poachers can chop out the tusks and make off with the ivory. Less than 20 minutes after the elephant was felled, Molteno located a clearing and put the helicopter down next to Kanisa's rangers. Every extraneous piece of equipment had been removed to make space for the rangers, who clambered in with their weapons. Everyone aboard the chopper had an AK-47 assault rifle. One clutched a grenade launcher.

The poachers had covered the dead elephant with camouflage—branches and thick stalks of grass—making it hard to spot from the air. Mararv and the rangers swept low over the area for the next 45 minutes, finally spotting an eddy of vultures, which indicated a carcass below. Molteno prepared to land. As the helicopter closed in, Mararv could see bloody hatchet marks in the animal's face, but the tusks, a modest 22 pounds each, were still in place, meaning the poachers were likely close by. Such tusks might earn a few hundred dollars for the poachers, but by the time smugglers ship the raw ivory to China, it could fetch more than $14,500.