Benjamin has escaped from an ordinary life to adventure on the High Seas, only he's way over his head. He's jumped into a smuggling scheme where he's posing as a notorious Captain, only he knows about as much about sailing as any lubber. When he finds himself ship-wrecked on a desert isle with a dark reputation, he's not any better off, having only lived in more civilized surroundings.
Sun (an Anglicized version of his name given by Benjamin, rather like Defoe's Robinson Crusoe christened his Friday), is man who has escaped the pirates that had him enslaved. Fortunately for Benjamin, he knows much better how to survive and saves Benjamin's life.
There is a lot going on in this book. There are historical political and social details that impact the events. The voices (in speech and thought) of the characters pay homage to the period. Benjamin struggles with his attraction to men, as the son of a preacher who regularly made sure to beat things out of him. He also has moral issues with some of the cardinal sins, despite his involving himself with plots and smugglers. But never fear, these things help set the period and are mostly a subtext rather than plot points. There are also so many micro-tropes played with here-- the twin from different parents, shipwrecked, mysterious island (with a volcano!), white slave, forced to fight in the pits, Man Friday... and that's only in the beginning of the book! But again, never fear, the story goes beyond the toying with these, so that they are almost throw-aways, put there for pure fun.
Benjamin and Sun do not immediately make a sweet couple. They each have their issues and flaws. But it is an exciting journey to go with them as they figure themselves out, become better men, and ultimately forge their fate together.
[Sex is had, but handled lightly with historical terms. There is rape, but handled similarly and briefly.]