Back to Africa (The Blind Sleuth Mysteries Book 15‪)‬

While visiting her son Jonathan in prison, Daisy heard a strange story. He'd befriended an old man who was serving a life sentence for a crime he hadn't committed. Of course every inmate says that, but Johnny-John believed this man's protestations of innocence and begged his mother to look into it.
The facts of the case had taken place in Zambia long ago, when it was a British colony, so Daisy started her investigation among ex-colonials who'd returned to England. However, it soon became clear that the people holding the key to the mystery were still living in Africa, so Daisy took a flight to Lusaka to seek out these witnesses.
The truth turned out to be as strange as life in the African bush can be. It slowly emerged from a missionary daughter's rambling memoir about the long-lost world she grew up in. Daisy had to follow a winding trail, but in the end she was mysteriously led to unexpected revelations.