In Ireland in 1905, Percy Fawcett (Charlie Hunnam) is a young British officer participating in a hunt on the land of an Irish baron, an event organized on the occasion of the visit of Franz Ferdinand, Archduke of Austria. A good rider and targeting, he hunts easily, but he is left out of the hunt party. A year later, Fawcett is sent to London to meet with officials from the Royal Geographical Society. The governments of Bolivia and Brazil are about to start a war because of the border separating the two countries. The two governments have urged the British Government to oversee the issue in order to avoid a war. Fawcett agrees to go to run the assessment team in the hope that he will be able to restore the good reputation of his family. On his way to Brazil, Fawcett meets Corporal Henry Costin (Robert Pattinson), who knows the Amazon jungle very well. On a vast plantation owned by the noble Portuguese Baron de Gondoriz, the two meet with Corporal Arthur Manley, who tells them that the British government recommends that further exploration be stopped. After completing his mission and returning to his native lands, Fawcett is raised to glory and his wife, Nina (Sienna Miller), has just given birth to her second little boy. In the Trinity College Library, Nina discovers a story that tells the story of a city in the depths of the Amazon Jungle. Fawcet later meets with renowned biologist James Murray, who agrees to accompany him back to the Amazon jungle in an attempt to find what he calls “The Lost City Z”.