Spencer Tracy’s performance is excellent in this film about Henry Stanley, a British-born journalist working in America, who is sent by his editor on an expedition into the African interior to locate David Livingstone, after reports of his death appeared in respected British newspapers. Equipped with funding and accompanied by his loyal companion "Slocum" (Walter Brennan), they begin their journey, eventually finding assistance from a sickly British consul in Zanzibar, and crossing Africa to face considerable challenges. The story is rooted in actual events, so the outcome of their travels isn't really in question, but the movie focuses on exploring what drives both men and how those motivations shift as they encounter the harsh realities of the continent and its inhabitants, influencing their perspectives and values. Sir Cedric Hardwicke portrays the missionary explorer with a sense of inherent, though somewhat privileged, morality, while Charles Coburn (Lord Tyce), the publisher of a competing newspaper, seems quite keen on Stanley’s failure. Even if Brennan isn't known for his range, he provides dependable support throughout. Filming on location allows for expansive views of their adventures and Tracy and Hardwicke’s measured acting style makes this film worthwhile viewing.

Source on TMDB