Night Runners by Richard Crompton
On Mollel's return from Hell's Gate he is put on duty in Dandora, a Nairobi slum infamous for its teeming rubbish dump - home to scavengers and shadowy rulers - and Night Runners, who are said to be possessed by the devil. While witnessing a near-riot, Mollel is approached by a young girl called Miriam who is refusing to speak to anyone other than the 'Masaai cop'. Miriam's sixteen-year-old sister Fatima has disappeared, and Fatima's school and father - an ambitious local councillor - seem to be covering something up.
So begins an odyssey into Nairobi's underworld which will take Mollel - aided by his streetwise son Adam - from rap clubs to voodoo healers, as the detective tries to find the missing girl and come to terms with his fractured past in a city where no one will tell him the truth.