Classicly

Although the book's title Black Ivory denotes dealing in the slave trade it is not our heroes who are doing it. At the very first chapter there is a shipwreck, which leaves the son of the charterer of the sinking ship, and a seaman friend of his, alone on the east coast of Africa, where Arab and Portuguese slave traders were still carrying out their evil trade, despite the great efforts of patrolling British warships to limit it and free the unfortunates whom they found being carried away in the Arab dhows.

This book will open your eyes to what really went on. At the time of writing slave-dealing on the west coast of Africa was, due to the efforts of the British, almost extinct, but this was not the case on the east coast.