The River Thames is an essential part of the plot and the aesthetics of Our Mutual Friend. The river winds through the city and the surrounding towns, uniting the rich and the poor alike despite The Rigidity of Social Class: The same river on which the poor boatmen float back and forth in search of ill-gotten gains facilitates international trade and brings John Harmon back from his exile abroad. The dirty, polluted river runs thick with the waste of the city, creating a unified symbol of the cost of London’s success. The Thames becomes a symbol of the pollution at the heart of the society itself; from murder to blackmail to the predatory practices of wealthy and poor people alike, the dirty river brings everyone together and mires them in the pollution of immorality.

Amid this corruption and pollution, the Thames plays an important narrative role. The story begins with a body being fished out of the water by Gaffer Hexam. This act is rife with the immorality that the river symbolizes, as Hexam searches the dead man’s pockets for any money. This is not the first body that will be found in the Thames; even Hexam himself will fall into the river and drown, implying that he has fallen victim to his own corruption.