George Pelecanos's Washington, D.C., is a far cry from the upwardlymobile, tourist-attraction-speckled enclave of Margaret Truman (Murder at the National Cathedral, Murder in Georgetown). Pelecanos's capital is a haunting terrain of drugs and death, a no man's land of posturing dealers and skeletal warehouses that shelter their buyers:A rat scurried into a dim side room, and a withered black face receded into the darkness. The face belonged to a junkie...