This tale of the man who built the Suez Canal is a mixture of fact and fiction.
In Paris in 1850 President Louis Napoleon (Leon Ames) sees Countess Eugenie de Montijo (Loretta Young) rooting for tennis player Ferdinand de Lesseps (Tyrone Power) and invites them to a ball. A swami predicts that Eugenie will wear a crown and that Ferdinand will dig ditches. Ferdinand asks Eugenie to marry before he leaves for Egypt; but she says no.
In Alexandria Ferdinand finds Tonie Pellerin (Annabella) swimming nude. He meets British diplomat Malcolm Cameron (Nigel Bruce) with his father Mathieu de Lesseps (Henry Stephenson), who tells Ferdinand to befriend Prince Sa'id (J. Edward Bromberg). Mathieu leaves Ferdinand in charge as consul. At the Suez isthmus Tonie takes a horse and follows Ferdinand. In a storm they take cover. Tonie is jealous. Ferdinand envisions a canal and asks the Turkish viceroy Muhammad Ali (Maurice Moscovitch) for the land; but Cameron says that England opposes a French canal. The Viceroy and Prince Said encourage Ferdinand.
Tonie and her grandfather (Sig Ruman) go to Paris with Ferdinand, who sees Eugenie riding with Louis Napoleon. Victor Hugo says that Louis Napoleon is provoking rioting to adjourn the assembly. Eugenie asks Ferdinand to help Louis Napoleon by getting the assembly to adjourn temporarily. Then Louis Napoleon orders arrests except for Ferdinand. His friend Rene de Latour (Joseph Schildkraut) is arrested, and he blames Ferdinand. Mathieu de Lesseps dies of a stroke. Tonie escapes school and goes to console Ferdinand. Eugenie comes to explain that Louis Napoleon broke his promise, but she says he offers the canal. Ferdinand gets a telegram that Said is now viceroy.
Canal work begins, and thousands labor. Ferdinand learns that Arabs stole explosives; their sabotage kills many, but Sa'id finds it was Turks. Tonie writes Ferdinand that Eugenie wed Louis Napoleon, and prisoners were pardoned. Tonie and Rene learn that Louis Napoleon is stopping the canal to please England from fear of Prussia. Eugenie says she has faith in Ferdinand, who tells Rene and Tonie that he must go to England. There the Prime Minister says Britain should refrain from foreign adventures; but Benjamin Disraeli (Miles Mander) argues for British power. Ferdinand appeals to Disraeli, who encourages him to raise money.
Viceroy Sa'id sells jewelry. A tornado destroys much, and Tonie saves Ferdinand; but she is killed. Ferdinand tells Rene that he failed. Disraeli wins the election and supports the canal. Eugenie presents Ferdinand with honors. In the final scene Ferdinand hears the voice of Tonie that he built the canal for all the people of the world.
De Lesseps' diplomatic career was ruined by a controversy in Italy, not as portrayed in this film. Eugenie was Ferdinand's cousin and supported the canal project. The canal was begun in 1859, and Empress Eugenie attended the opening in 1869. Disraeli's British government did not purchase a majority of the shares until 1875.