Joan Aiken 
Limbo Lodge [EPUB ebook] 

Dido Twite is aboard the Thrush, trying to return to England after her adventures in America. But orders have been sent to find Lord Herodsfoot, said to be on Aratu, the Pacific ‘Island of the Pearl Snakes’. Snakes are the least of Dido’s worries as she and her companions struggle through the jungle. On Aratu she is helped by spirit magic but also meets settlers who will stop at nothing to achieve their ends. And what is this strange royal residence called Limbo Lodge?