On one traumatic night in July 2016, a faction of the Turkish military tried to overthrow the government. The coup failed, but hundreds of people were killed. President Erdogan said it was the work of the US-based cleric Fethullah Gulen and his supporters. Gulen denies involvement, but President Erdogan has vowed to 'cleanse the virus' behind the coup attempt and thousands of Turks, accused of being Gulenist sympathisers, have lost their jobs. Tim Whewell reports.