Overcrowded and desperately poor, Nairobi’s slums are a concentrated and explosive mix of apparently insolvable problems: gang violence, ethnic tensions, drug and alcohol abuse, rapes, corruption, epidemics, prostitution, street children, water pollution, illicit trafficks, arms’ dealings, HIV.  Churches and Ngos fight an uphill battle against crime and deseases. Some grannies even resort to martial arts hoping to fend off sexual assaults.