1867. King's Road, Chelsea, is a sea of plant nurseries, catering to the Victorian obsession with rare and exotic flora. But each of the glossy emporiums is fuelled by the dangerous world of the planthunters – daring adventurers sent into uncharted lands in search of untold wonders to grace England's finest gardens.

Harry Compton is as far from a planthunter as one could imagine – a salesman plucked from the obscurity of the nursery growing fields to become 'the face that sold a thousand plants'.

But one small act of kindness sees him inherit a precious gift – a specimen of a fabled tree last heard of in The Travels of Marco Polo, and a map.

Seizing his chance for fame and fortune, Harry sets out to make his mark. But where there is wealth there is corruption, and soon Harry is fleeing England, rounding the Cape of Good Hope and sailing up the Yangtze alongside a young widow – both in pursuit of the plant that could change their futures.