Egypt has filled its prisons with some 40,000 people since the 2013 coup, the vast majority of them young activists of the now-banned Muslim Brotherhood subjected to torture and mistreatment. And so once again the country is turning out a new generation of violent radicals. In this illuminating history of the links between the country’s prisons and violent extremism, the complex history of the Sinai based ISIS affiliate that weeks ago blew up an airliner full of Russian tourists, murdering more than 200 people: