The town in which the play is set has built a huge bathing complex that is crucial to the town's economy. Dr. Stockmann has just discovered that the baths' drainage system is seriously contaminated. He alerts several members of the community, including Hovstad and Aslaksen, and receives generous support and thanks for making his discovery in time to save the town. The next morning, however, his brother, who is also the town's mayor, tells him that he must retract his statements, for the necessary repairs would be too expensive; additionally, the mayor is not convinced by Dr. Stockmann's findings. The brothers have a fierce argument, but Dr. Stockmann hopes that at least Hovstad's newspaper will support him. However, the mayor convinces Hovstad and Aslaksen to oppose Dr. Stockmann.