FORTUNE – It’s easy to think of Hawaii as a relatively untouched paradise. To surfers and tourists, its islands are known for miles of public beaches and vast oceanic surroundings, where volcanoes roar against the backdrop of pink sunsets. But in a new book, author Julia Flynn Siler shows another side of Hawaii that many tend to forget, or perhaps don’t know much about. Before it was annexed into the U.S., Hawaii was ruled for generations by a thriving monarchy. And before that, it existed in blissful isolation until Polynesian islanders first settled.

Lost Kingdom: Hawaii’s Last Queen, the Sugar Kings, and America’s First Imperial Adventure is the story of an island grappling to hold onto traditions in the face of burgeoning capitalist powers. If you happen to check out the recently released comedy drama, The Descendants, Siler’s book suggests why perhaps George Clooney’s character, Matt King, a descendant of Hawaiian royalty, struggles to sell off land his family has held for generations. Though the film is based on Kaui Hart Hemmings’ 2007 novel, Siler captures its backstory — essentially what Hawaii was then and what it has evolved into today.

What happened to the islands is known as one of the most aggressive takeovers of the Gilded Age. And Siler, a contributing writer for The Wall Street Journal, gives us a riveting and intimate look at the rise and tragic fall of Hawaii’s royal family using historical documents, letters (many of which had never been published), and diary entries.

At the center of Siler’s book is Lili’uokalani, Hawaii’s last queen who eventually loses her throne. Born in 1838, she witnesses the transformation of the islands. When missionaries from Boston arrive, they convert the royal family to Christianity and set up missionary schools. Soon, Hawaii’s agricultural lands start piquing the interests of a small group of so-called Sugar Kings, almost exclusively white planters. They develop lucrative sugar plantations around the islands and eventually control the majority of arable lands.

The most notable of these is Claus Spreckels, a German immigrant and grocer turned sugar refiner who eventually buys up half of Hawaii’s sugar crop. Becoming one of the richest, if not the richest, men on the islands, Spreckels becomes a major lender to the royal family and helps drive them deeper into debt. Spreckels’s vast wealth can still be seen today in several California enterprises, including Spreckels Sugar Company, while his descendants own swaths of Napa Valley (and, as Siler notes, the romance novelist Danielle Steele owns the Spreckels “Sugar Palace” mansion in San Francisco).

By the time Lili’u rises to the throne, the powers of the monarchy have waned, compromised by wealthy sugar plantation owners. The queen tries to enact a constitution that would reinstate its powers, but she’s eventually defeated, and Hawaii becomes a trophy of sorts among the U.S., Britain, and France — each vying to expand their military and commercial influences in the Pacific. By January 1893, the U.S. begins to take over Hawaii in a controversial annexation that President Grover Cleveland opposed.

It becomes abundantly clear that nearly every foreigner who stepped onto the island saw something special and wanted to capitalize on it at the expense of native Hawaiians. In a way, Siler leaves us wondering what Hawaii could have been if missionaries had never arrived, if the planters were never drawn to its sugar plantations, and if the concept of “manifest destiny” hadn’t taken hold in the U.S.

Nevertheless, the book is a reminder that Hawaii remains one of the most breathtaking places in the world. Even if the kingdom is lost.