Karachi has become one of the most dangerous cities in the world. An explosive mix of crime, corruption and Islamic extremism. Even mayor, Syed Mustafa Kamal, acknowledges that Karachi is ‘the economic locomotive of the Taliban’. But the city that harboured the Bombay Bombers has also experienced more than its fair share of carnage: at least 50 people were killed in a suicide attack in January 2011. We profile this complex city.