Giovanbattista Parodi, scion of the bourgeois Genoese ship-owners, is a young doctor in the Royal Navy who becomes a deserter after the disastrous battle of Lissa. He must find a new shipboard job to flee from the authorities and his remorse about an unmentionable crime. After arriving in Marseilles, he ends up by chance on board of an elegant commercial windjammer, the Neptune, captained by a mysterious and evasive Spaniard. Captain Blanco does not seem particularly interested in the secrets Parodi is hiding; perhaps because he doesn’t want too many questions about his activity, his ship or his cargo. When the Neptuno touches the coast of Dahomey, it unloads weapons and takes ivory on board, but instead of setting sail for Cuba, its supposed destination, it sails South along the coast of Africa. During the voyage, Parodi’s apprehension and uneasiness grows as everything around him changes: his shipmates, the scenery and even the ship undergo a bleak metamorphosis. Finally, one day, the Neptuno shows its true face: 350 human beings are dragged on board in a crescendo of brutality and horror, and stuffed into the hold like animals. Unable to leave the ship, the young doctor tries as hard as he can to offer relief to these people in hell, continually defying the crew’s ferocity and indifference. The voyage of the slave ship seems to be a descent into Hell with no return. But the shining eyes of Nyatà, proud and majestic even in these conditions of misery, change everything. Even the colour of the sky in which the sun can shine again.