Islands of Mercy by Rose Tremain

In the city of Bath, in the year 1865, an extraordinary young woman renowned for her nursing skills is convinced that some other destiny will one day show itself to her. But when she finds herself torn between a dangerous affair with a female lover and the promise of a conventional marriage to an apparently respectable doctor, her desires begin to lead her towards a future she had never imagined.

Meanwhile, on the wild island of Borneo, an eccentric British ‘rajah’, Sir Ralph Savage, overflowing with philanthropy but compromised by his passions, sees his schemes relentlessly undermined by his own fragility, by man’s innate greed and by the invasive power of the forest itself.