Throughout their privileged but highly eccentric childhood Jack Rathbone has enjoyed the constant adoration of his sister Gin. When both attend art school in London, Jack plunges into a passionate affair with Vera Savage, a painter some years his senior, and they soon run away to New York. From a bruised and bereft distance Gin follows their southward progress to Miami, then Havana, and so to Port Mungo, a wilting swamp town on the steamy Gulf of Honduras. There Jack devotes himself to his art, and works with a fervour as intense as the restless, boozy waywardness to which Vera succumbs, which even the birth of two daughters cannot subdue. As the tension builds, a tragedy occurs that will tear apart not only their world but that of Jack's watchful sister, Gin.