The shadow of violence hung over West Bengal this week. In Burdwan, an hour north of Kolkata, an accidental explosion may have revealed the presence of Bangladesh-based Islamist militant groups, using Bengal to carry out strikes here or across the border. The shock revelation comes at the same time as a sharp escalation in clashes between the ruling Trinamool Congress and its newest political foe in the state in Birbhum. Both episodes are not unconnected, linked by deep misgivings about the Trinamool Congress' pandering to religious extremism and fostering a culture of political violence that poses not just a security risk, but also a risk to Chief Minister Mamata Banerjee's political future.