The Jungle Twins were American adventurers in Africa.
In 1920, near the Gold Coast of Africa, Dr. Wilbur Dale and his family and their expedition were attacked and massacred by hostile Bushmen. The Dales had twin 2-year-old sons, Steven and William. William was rescued from the fray by one loyal nursemaid, Moma, who carried him away into the jungle. After an eventful journey, she ended up carrying the tot to New York City, and handing him over to Mr. Brown, Bill's late father's attorney, and his new court-appointed guardian.
In 1940, Bill undertook an expedition to Africa, to seek out his brother Steven, whom he (correctly) believed to be still alive. After weeks of searching, Bill found Steve in a remote and unusual region in Africa, the Region Beyond the River of Skulls. Their initial meeting went very badly, and they were lucky to survive it.