Murphy is the sole survivor of his crew, that has been massacred by a German U-Boat in the closing days of World War II. He is rescued, and ends up at a forgotten mission station near the mouth of the Orinoco, and begins to plot his vengeance. He wishes to sink the U-Boat by means of any method imaginable to him, and sets about to make the courageous attempt, assisted by Louis, the administrator of the local oil company.
