"A Frontier Mystery" by Bertram Mitford has to do with the murderous rites of the 'Brotherhood of the Dew,' a superstitious sect of the Zulus on the borders of Natal in Afrtica, who had a horrible way of sacrificing human beings in order to bring rain during times of drought. This is only discovered after the mysterious disappearance of two white settlers. Conflicts, murder, and disappearing foreigners will keep readers engaged until the last page.