In a chilly autumn, a series of terrible crimes occurred on Westminster Bridge, which runs across the Thames from the Houses of Parliament: three men were stabbed to death one after another. The public is horrified - after all, all three were parliamentarians, members of the House of Commons. Police Inspector Thomas Pitt is tormented by the question: in which direction to look for the killer? Robber? But none of those killed were robbed. Political speech? However, during their lifetime, parliamentarians held different views on the most pressing policy issues. Provocation of anarchists? But the method of murder is not suitable - they prefer bombs...