Emily and Alexander travel to Africa to visit their cousin Safari Sue. She lives with the girl Taimani, who is teased by the other Maasai children because of her height. Everyone scoffs that she is to become the wife of a ghost who lives in the mysterious Black Mountain. Since this is shunned by the Maasai, the diamond digger DeClerk has an easy time of it. He can carry out blasting in the mountain in peace and steal the diamonds.