The British Prime Minister (Herbert Marshall) assigns a mission to an explorer (Cedric Hardwicke) who is surveying West Africa by balloon. Namely to plant the British flag on an uncharted area for the crown before the land can be claimed by slave traders. Loosely based on the Jules Verne novel, this is an undemanding comedy/adventure film for "the whole family" as they used to say. It's rather silly and the portrayal of the Arabs and African natives are cartoonish but there's an air of innocent fun. The narrative is often illogical. For example, Peter Lorre plays an unrepentant slave trader who is forced to travel with the explorer's group against his will but when he gets a chance to escape, he doesn't and not only that but helps them rather than turning them over to his cronies! But it's not the kind of film that holds up under analysis. There are some second unit shots of Africa in CinemaScope but the film itself was shot on the 20th Century Fox sound stages. Directed by Irwin Allen. With Red Buttons, Barbara Eden, Fabian, Barbara Luna, Richard Hayden, Henry Daniell, Mike Mazurki and Billy Gilbert.