In a small Norwegian town, Catherine Stockmann, the wife of Dr. Thomas “Tom” Stockmann, prepares to entertain prominent members of the community, including the People’s Daily Messenger newspaper editors, Hovstad and Billing. Tom returns home with his two young sons, Morten and Ejlif, as well as his friend, Captain Forster, who is included among the dinner guests. Before the event begins, Tom’s brother, Peter Stockmann, arrives for a routine medical examination. As the town’s judge and mayor, Peter also serves as chairman of Kirsten Springs, the community’s new tourist destination and the foundation of its economy. Tom, who is the Springs’ medical examiner, has recently conducted a study of the water and is awaiting its results; Peter is pleased to learn that Hovstad and Billing will publish Tom’s findings before the summer season to promote tourism. Hovstad credits Tom with originating the plan to capitalize on the town’s natural resources, but Peter claims that he alone had the wherewithal to establish the business and leaves the house in anger. As guests sit down to dinner, the Stockmann’s eldest child, Petra, runs to the table with mail for her father. After reviewing the letter’s report in his office, Tom returns to his family and friends with terrible news: Kirsten Springs is polluted with bacteria from a nearby tannery owned by his eccentric father-in-law, Morten Kiil. Before construction began, Tom warned that it was unsafe to build a pipeline so close to a mill that dumps waste into a nearby river, but Peter prioritized cost reduction and expediency. Although the town’s water is now contaminated, Tom is convinced that conditions can change for the better with a new waterworks system. Placing the report and his article in an envelope, Tom has his maid, Randine, deliver the findings to Peter. Meanwhile, Hovstad and Billing insist on including the story in the following day’s newspaper, even though the official report is in Peter’s possession. Later that evening, Tom receives a reply from Peter, but tucks the report away before Catherine can see it. In the morning, her father, Morten Kiil, visits the Stockmann home, skeptical about Tom’s findings. Later that day at a tavern, Tom meets Hovstad, who intends to portray the story as a scandal invovling the town’s corrupt bureaucrats. Just then, the People’s Daily Messenger publisher, Mr. Aslaksen, joins the table and promises to galvanize the community with a public demonstration, but Hovstad suspects Peter Stockmann will try to cover up his brother’s findings and turn the town against him. Upholding Peter’s integrity, Tom gives Hovstad the report in good faith, promising that it is fit for print once he has discussed the data with his brother. Back at the Stockmann home, Peter antagonizes Tom and declares that the decontamination plan will cost 300,000 kroner. Peter appeals for Tom’s “discretion” in revealing his findings, but Tom warns that the danger to human life could reach epic proportions if the truth is suppressed. He also reveals that Hovstad and Billing are preparing to print the report. Threatening Tom’s career and family, Peter orders his brother to publicly denounce the article and endorse the Kirsten Springs board. Tom later visits the People’s Daily Messenger and consents to the publication of his report. When he leaves, publisher Aslaksen suggests a moderate approach toward the article, since it could create a backlash against the newspaper. Shortly thereafter, Peter arrives at the office, claiming he will tax poor and middle-class townspeople to pay for the new waterworks, even though Kirsten Springs is a privately owned corporation. Peter claims that his brother fabricated the report to defy authority, and Aslaksen fears the town’s economy will collapse under the new taxation. As Peter procures an alternate “report,” the publisher agrees to cover up Tom’s findings to save the town from financial ruin. Just then, Tom returns to the office and Peter hides to conceal his arrangement with the newspaper. When Tom sees his brother’s walking stick, he realizes his allies have been swayed. He retrieves his report and insists on leading a town meeting the next day. By the time of the gathering, however, the townspeople have already been biased in favor of Peter’s false report. The mayor declares that his brother is a threat to democracy, and promises that the springs will bring prosperity to rich and poor members of the community. When Peter argues that his brother should not have the right to read his report, Aslaksen calls for a vote. Realizing the town has turned against him, Tom declines to present his data. Instead, he warns that democracy is not foolproof, since the decisions of the majority can ultimately be wrong. As the crowd responds with rage, Aslaksen reads a motion to proclaim Tom an “Enemy of the People.” With the exception of Captain Forster, all citizens agree to deny the doctor’s civil rights. Upon returning home in a snowstorm, the Stockmanns are greeted with stones thrown through their windows and an eviction notice. Tom plans to move his family to the U.S. on Forster’s ship, but Catherine does not want to leave. Meanwhile, Petra is dismissed from school for being a “radical.” Just then, Peter arrives with news that Tom has lost his job, but he can re-establish his career by retracting the report. Tom also learns that his father-in-law, Morten Kiil, has spent the day amassing Kirsten Springs stock for half its original value. Noting that Morten is capitalizing on the repercussions of Tom’s report, Peter threatens to punish his brother as a conspirator, but Tom refuses to give in. Sometime later, Morten visits his son-in-law with a fist full of Kirsten Springs bonds. Reminding Tom that the Kiil family has owned the polluting tannery for generations, Morten declares that he used Catherine’s inheritance to purchase Kirsten Springs shares. In Morten’s blackmail scheme, Tom must accept the bonds to retain his family’s wealth. In doing so, however, he will own an enormous stake in Kirsten Springs, and is therefore obligated to recant his report to protect his investment. As Morten leaves, Hovstad and Aslaksen arrive to suggest a new approach to the crisis. Since Morten bought the Kirsten Springs bonds in the Stockmann family name, the People’s Daily Messenger can publish articles that convey Tom as a hero, showing townspeople that he purchased the stock to implement his changes. In return, Hovstad requests payment from Tom to cover the newspaper’s financial loses. Realizing that the only way to clear his name is to become corrupt, Tom declares that the community is as poisoned as its water. After chasing Hovstad and Aslaksen from his home, Tom announces that the family will stay put and fight for the truth. While the Stockmanns cover their broken windows, a barrage of rocks are hurled through the windows of Tom’s office.