It is loosely based on the true story of Welsh reporter Sir Henry M. Stanley's quest to find Dr. David Livingstone, a Scottish missionary presumed lost in Africa, who he finally met on November 10, 1871.

Other cast members include Nancy Kelly, Richard Greene, Walter Brennan, Charles Coburn and Henry Hull.

Colonel Grimes tells two peace commissioners sent from Washington DC that he cannot permit them to try to contact the Indians of the Wyoming Territory of 1870, as it would be suicidal, only to have Stanley emerge from the wilderness, escorted by a band of the natives and his guide, Jeff Slocum.

It is a daunting task, searching the mostly unmapped interior of the "dark continent" for one man, but Stanley accepts the challenge.

On the boat trip to Zanzibar, Stanley makes a very unfavorable impression on fellow passenger Lord Tyce.

As he is leaving the hall, a messenger arrives with news that another expedition has recovered Livingstone's body, as well as the man's last written message, in which he talks glowingly of Stanley.

According to Philip Dunne, the film was originally envisioned as a vehicle for Tyrone Power as Stanley with the script prepared accordingly.

Darryl F. Zanuck, head of production at 20th Century Fox was sent a memo suggesting the project be changed to be about a more cynical Stanley who looks for Livingstone as a publicity stunt, then becomes idealistic after meeting him.