Sent from London to Africa on a secret government mission, British explorer Alec McKenzie is persuaded by Lucy Allerton, his fiancée, to take along her no-good brother George, who, after losing his job because of alcohol, is in need of manly experience. Also on his expedition are Dr. Adamson, and McInnery, Lucy's former suitor. Alec treks into the wilds of Africa and negotiates settlements with the local tribes to stop the slave trade. Before the treaties are made official, however, George gets drunk, attacks a native girl, and shoots her African lover when he comes to her rescue. The tribesmen declare war on the intruders, and the suddenly repentant George volunteers to stay behind and cover the others while they slip away to the river, a brave effort that results in his death. Alex promises to keep the details of George's sacrifice a secret and suffers rejection from Lucy, who believes McInnery's story that Alec abandoned her brother to save himself. Unable to endure the injustice in silence, Dr. Adamson finally tells Lucy the truth about her brother's dishonor, and she forgives Alec for trying to spare her.