The book starts in 2003, in the auction rooms of J. Thomas & Co (India's oldest firm of tea brokers and auctioneers, established in 1861) as one lot of Darjeeling tea - a fine Silver Tips Imperial picked under a full moon - is about to break the record for tea sold at wholesale auction. The lot eventually goes for US$390.70 a kilogram - or, as Koehler puts it, 250 times the country's average for tea at auction. It's a marker of Darjeeling's reputation and of just how highly prized the unique qualities and tastes that teas from the region possess have become.

That tea was even grown in Darjeeling in the first place was an accident, according to Koehler. A mountainous Himalayan region in northeastern India sandwiched between Nepal, Bhutan and Tibet, Darjeeling was never considered a likely spot for the planting of tea. Yet, as Koehler writes: "In the cool, high elevation and thin air, the buds grow slowly, allowing flavours to develop and concentrate."

Tea is a US$90 billion global market, yet despite its reputation the area formed by Darjeeling has just 87 tea estates, with a grand total of 19,500 hectares of plants. Combined, they produce less than 1 per cent of India's total tea production; given deforestation regulations and the rugged and mountainous landscape that figure is unlikely to change: Darjeeling's tea estates have expanded as far as they are ever likely to and already cultivate as much land as they possibly can. For all its reputation, Darjeeling will always be a small, high-end corner of the global tea industry.

traces the region's history back to the arrival of tea in Europe's consciousness: its first appearance in 1580, when a Portuguese trader brought a chest of tea back from China along with silks, spices, porcelain and lacquered objects, and the subsequent involvement of the East India Company in the trade, shipping its first chests back from China in 1664.

We see the growing sense, later brought into stark relief by the opium wars, that Europe desperately needed to diversify its supplies; by 1766, just one century after it first began shipping tea to Britain, the East India Company was already importing 2.7 million kilograms of it a year from China.

Koehler then turns his attention to India, charting the successful attempts by Europeans to smuggle seedlings out of China to India - along with experienced Chinese tea growers who could guide outside cultivation - and the unexpected finding of indigenous tea growing in northeastern India. Finally, after what feels like a monumental journey, we arrive in Darjeeling.

Koehler manages to bring this history to life through the individuals who inhabited these times and through his vivid descriptions of the landscapes.

Although just 80km by road from the nearest airport, the trip to Darjeeling still takes four hours through mountainous passes. In the 1800s it was even more isolated, and until a rail link was established in the 1880s the journey from Calcutta to Darjeeling took months, ending with a long horse ride, walk or litter ride up to the hill station. "The hazardous, uncomfortable trip was made only by the desperate or the determined," Koehler writes.

The 357 sq km tract of land had been extracted from the rajah of Sikkim, a local ruler, in exchange for a rifle, a shotgun, 18 metres of red broadcloth and two shawls, and was originally a hill station retreat for East India Company employees needing to convalesce from the many diseases one could pick up in India, or to escape the summer heat in "oases of European civilisation".

However, it wasn't long before tea came to dominate, changing the landscape forever. One Victorian tea planter writing at the time described an extended line of men clearing the jungle for tea "cleaving their way steadily and surely through the dense undergrowth and bamboo jungle, dexterously swinging their peculiarly-shaped (half axe, half sword) …"

Koehler is clearly drawn to the romance of the mountainous location, the colonial vestiges that still remain, and the passion of those individuals past and present who've dedicated their lives to growing tea in the region.

We are introduced to Nathaniel Wallich, a Dutch surgeon who became a prisoner of war to the British during the Napoleonic wars, when Denmark allied with France, only to be released and transformed into the East India Company's chief botanist in India. Louis Mandelli, a young man from an aristocratic Maltese family who arrived in Darjeeling in the late 19th century with a bang, only to fail in his ventures and ultimately commit suicide a few years later.

Contemporary individuals include Rajah Banerjee, whose great-grandfather founded the Darjeeling estate he now runs and who taste-tests new leaves as others would a fine wine, slurping, sniffing and repeatedly saying, "Damn good! Damn good!", when he finds a cup that impresses him (and grimacing and dramatically spitting out teas that offend).

At the same time Koehler delves into the current realities for the region, which are not so rosy. Darjeeling teas are mostly single-estate teas, unblended and unflavoured to allow their natural strengths to come out. It is an at-times archaic world where artisans produce teas using methods and tools that have barely changed in a century and where tens of thousands of women (and it is always women) pluck the leaves by hand every year.

With growing aspirations among India's working class, tea estates are finding it hard to retain staff, and at the same time are fighting a losing battle against counterfeiters - industry insiders estimate that around 40 million kilograms of "Darjeeling tea" are sold each year, four times the amount the area actually produces - and competition from tea growers in Nepal and Kenya. Profit margins are thin and nowadays tea estates in Darjeeling are lucky if they even make a profit.

Interestingly, most of its teas are exported; Indians generally prefer stronger teas mixed with plenty of milk and sugar rather than the subtle, delicate and fragrant flavours of Darjeeling's teas.

The book is an engaging read, although at times the author seems to look back too wistfully on the days of British colonial rule - the European-only clubs, the afternoon socials and the determination of strangers in a strange land. Yet despite this, Koehler has the knack of a good storyteller who has found a great story to tell.

Tea may have only been planted on the slopes of Darjeeling a century and a half ago but it has been a truly fascinating 150 years - and makes you want to put the kettle on and have a cup.