Never heard of Poyais? That's because you weren't living in Great Britain in the early 1820s, when newspaper advertisements, promotional brochures and the ubiquitous street singers broadcast the country's limitless opportunities to potential investors. There was a snake in the garden, though, writes David Sinclair in "The Land That Never Was," a striking and colorful history of Poyais. The glitch: Poyais was a fiction, the brainchild-turned-hell-spawn of Gregor MacGregor -- fantasist, confidence trickster, dandy and bon vivant with a taste for titles and palms itching for lucre. Mostly, MacGregor sat on his hands. When roused, he made tactical and logistical...