January Marlow is one of three survivors of a plane crash on the island of Robinson. They have to wait for three months for the arrival of the pomegranate boat to get back to civilization. Their host Robinson is a taciturn, not very welcoming host who wants them gone as quickly as possible and has to tolerate them - just barely whilst they are there.
On Robinson's suggestion January maintains a journal not realizing the journal could be the cause for her murder. On this tropical little island a mix of everything comes to play - a disappearance which very much looks like murder, a boiling volcano called the Furnace, sexual tension and sexual competition, an orphan whose origins are shrouded in mystery, blackmail, mystery and adventure.
All this packed into a little book. This is the clever bit. The descriptiveness of the story is one of the highlights of this book - they stay in your head long after the book is read "the mustard field staring at me with a yellow eye" is one which will stick with me for a long while!