The situation also takes a toll on Lionheart's mental health, with his temper more unruly than usual, and unintentionally taken out on Dawn Bellwether. With his afternoon cleared courtesy of his assistant, Lionheart visits the asylum for updates, only to find that the cause of the outbreak is still unknown. Frustrated with the delays, Lionheart confronts Dr. Badger on her incompetence, to which the latter responds by hypothesizing the outbreak to be linked to "biology". She explains that the only animals going savage are predators, implying that they may be reverting back to their primitive instincts. Badger then advises Lionheart to inform the public of the dire situation, but the mayor refuses, knowing the balance between predator and prey would be broken out of fear should word get out, while also alluding to his own personal insecurities, as the rapid distrust towards predators, such as himself, could ruin his reputation. When asked about Chief Bogo's thoughts on the matter, Lionheart admits that Bogo is being kept in the dark. Just then, Lionheart hears the ringtone of a phone, and removes himself from the scene while Badger alerts the guards. The spies were Judy and her accomplice, Nick Wilde, who recorded Lionheart's admission and subsequently informed Bogo of the operation.

The asylum is raided that night, and Lionheart is arrested. As Bogo and Judy escort him to a patrol car, Lionheart explains that he was trying to protect the city, though Judy accuses him of caring for his job and nothing more. Lionheart warns Judy of the danger that the savage outbreak holds, and if a cure can't be found, it could lead to the destruction of Zootopia; his words are nevertheless dismissed, and the former mayor is removed from office. Bellwether, meanwhile, rises to power in his place.

Unfortunately, Lionheart's fears were correct. The news that predators are the only mammals going savage causes citywide panic, with prey mammals developing a heightened fear of predators, who in turn face direct discrimination and injustice. Over time, more predators mysteriously fall under the infection, leading to public attacks, though Lionheart was now powerless to suppress it.

In the end, however, it is revealed that the predators were not turned by biology, but through a drug concocted by Bellwether's henchman from Night Howler flowers, in her scheme to get predatory species ostracized from the city and usurp Lionheart. Due to Judy's heroism, Bellwether is arrested and removed from office, while the inflicted predators are successfully cured of their ailment. When informed and interviewed on the matter, Lionheart (who appears to be rather unfazed by the fact that he is in prison) explains that he had no knowledge of Bellwether's plot, but fully confesses his crime of illegally imprisoning the savage predators during his confidential mission to protect the city, confidently declaring it to have been done for the "right reasons".

During the end credits, a tranquil Lionheart is seen casually lounging in his prison cell while enjoying and sharing his thoughts on a magazine with his cellmate.