Edgar Wallace 
The Keepers of the King’s Peace [EPUB ebook] 

‘I want you to go up the Isango, Bones, ‘ said Sanders, ‘there may be some trouble there – a woman is working miracles.’ Unexpected things happen in the territories of the Belgian Congo where Commissioner Sanders keeps an uneasy peace, aided by his trusty assistant Lieutenant Hamilton and hindered, unintentionally, by the trouble-prone Bones. He must deal with ‘ju-ju’, ‘religious-palava’, lost vials of virulent disease…and all the while Bosambo, the magnificent king of the Ochori, watches on.