Tasmania, autumn 1912. Corto and Rasputine free a young man, Calaboose, imprisoned on an abandoned island. They take him with them through the Indian Ocean to Borneo, where they meet the Sultan of Sarawak, an English potentate, who reigns over the exploitation of the hevea by the natives. This natural resource is indispensable to the British Empire and the revolt that rumbles among the Dayaks threatens the interests of the crown. Corto finds himself playing the mediators and taking under his wing a young paralytic, Ratu "the mermaid", of which Calaboose falls in love. Corto and his friends then take the direction of the South Pacific and the island of Escondida, to find there the sponsor of their mission, the mysterious Monk, who has a very specific idea as to the future of the couple of lovebirds...