Two senior retired generals face charges of plotting to overthrow Turkey’s government on Monday as an Istanbul court begins hearing the second stage of a vast investigation into a clandestine ultra-nationalist network.

Two years after the discovery of weapons in a run-down Istanbul neighbourhood, the ever-widening probe into the “Ergenekon” network – named after the Turks’ mythical central Asian homeland – has become both a national soap opera and a deeply serious test of Turkey’s changing political culture.