What can be the research topic of the novel?

One possible research topic you might like to explore is the different understandings of civilization separating the Indians from the British. The British colonialists, having been in charge of India for centuries, regard themselves as civilized and their Indian subjects as little more than barbarians. Yet the mass uprising that leads to the siege of Krishnapur is caused by a general sense among the indigenous population that it is the British who are the barbarians. They are the ones who have intruded upon Indian civilization, a civilization that had endured for thousands of years before the colonialists arrived. The British are so secure in the artificial civilization that they've imposed upon India that they're genuinely taken aback by the sheer size and scale of the native rebellion.
Even after the Sepoy mutiny has broken out, many of the British civilians and administrators besieged at Krishnapur insist on maintaining their cultural superiority as if nothing has happened. Characters like Dr. Dunstaple cling tenaciously to a fanatical belief in the inherent strength and durability of Western civilization, even as their suffering mounts up as the siege drags on. Though far apart in many other respects, the British people trapped inside the garrison and the Indian mutineers raging outside the garrison's walls share something in common: they are both firmly committed to the belief that their civilization is the better one.