The irresistible force paradox – "What happens when an unstoppable force meets an immovable object?" – which was popularised by the film, The Dark Knight, can easily be used to describe the current political battle in West Bengal. Here, the mighty BJP led by Prime Minister Narendra Modi and Amit Shah has found a resilient opponent in West Bengal Chief Minister Mamata Banerjee.

Sunday's events – the Central Bureau of Investigation's (CBI) move against Kolkata Police Commissioner Rajeev Kumar, the West Bengal police's arrest of CBI officials, the CRPF guarding central government offices and, finally, Mamata Banerjee's "Save Democracy" protest – is only a dramatic manifestation of the high-stakes battle for West Bengal between the BJP and the Trinamool Congress.

What makes the Bengal paradox particularly difficult to understand is that both Mamata and Modi enjoy a high degree of popularity in the state.