THE LAST FLIGHT of the Scarlet Macaw centers around a small dam that should have gone up without a hitch. Planned for an undeveloped area of moist forest in central Belize, the 150-foot-tall concrete crescent promises to generate much-needed power during peak tourist season. But the story’s protagonist, a quirky expat zookeeper, worries that the dam’s reservoir will flood what could be the nesting grounds of the last two hundred scarlet macaws in Belize. This spurs a fact-finding trek into the jungle, and then other inquiries, until midway through the book it becomes apparent that the dam is profoundly flawed in many ways. “In twenty years of environmental advocacy,” Robert F. Kennedy Jr. is quoted as saying, “this dam is one of the most harebrained, reckless schemes I’ve ever seen.”

Indeed, the profile of a colorful local hero quickly morphs into a fascinating detective story. Barcott, a top-notch reporter who writes for the New York Times and is a contributing editor at Outside magazine, follows the kickbacks and secret contracts, the blustery government ministers and the press-shy scientists into the steamy habitat of the rainbow-colored parrots, the closed-door boardrooms of Canadian financiers, the offices of powerful environmental advocates, and ultimately the spirit of Belize, a young country that is corrupt to the highest level. An example? In the environmental impact statement’s dam-site map, someone literally erases a prominent seismic fault. A geologist hired by the government points this out . . . in a report that goes missing, and that the government refuses to acknowledge ever existed.

Barcott moves forward at a brisk clip. He sets vivid scenes — of a zoo, he writes, “the animals were cripples and orphans, the keepers castaways and dreamers, the signs hand-painted” — and limns wonderful characters with just a sprinkling of details — “a face carved from weathered mahogany: dark, thick, and runneled with creases.” Twice, he indulges in strident lectures on animal extinction, but soon enough he regains his cool and is back driving toward a courtroom ending more gripping than a Tuesday-night episode of Boston Legal. This is a wonderful piece of narrative nonfiction, one that will fascinate environmental activists, people who vacation in Belize, and lovers of mystery tales with whodunit suspense.