A small-town politician falls for an idealistic zookeeper.

Commodore John Balwind Parker, the corrupt boss of the most influential political machine in the town of Oakport, California, has just returned from Africa, where he has been on a hunting safari with his niece, Lily Rayton Parker. John and Lily proudly display their animal trophies at the city zoo, much to the disappointment of Dr. Kevin G. Maguire, the zoo superintendent, who does not believe in hunting wild animals. Kevin is later fired from his job, which angers his quick-tempered daughter Kathleen, who works as a tour guide at the zoo. Kathy knows that her father was fired because he opposed the commodore's decision to place his mounted trophies on the walls of the zoo offices. She shows her displeasure at the Parkers' influence on the zoo commission by interrupting their trophy presentation and protesting their cruelty to animals. An argument ensues between Lily and Kathy, and ends in a fistfight. When Kathy is charged with assault and battery, disturbing the peace and suspicion of inciting a riot, she turns to her friend, reporter Tim Harveigh, for help. Tim suggests that she appeal her case to attorney Andrew Rockton Hale, who is running for mayor of Oakport as a reformer and as a "champion of the underdog." Tim and Kathy are unaware, however, that Andrew has been making empty campaign promises and plans to align himself with Parker's political machine to get an advantage in the race. After meeting with Parker and realizing that Parker intends to make him his puppet, however, Andrew decides to postpone the alliance until he can better negotiate the arrangement through blackmail. Kathy unwittingly gives Andrew information with which to blackmail Parker when, while telling her hard luck story, she mentions Parker's corrupt influence on zoo officials. To prove her assertions, Kathy takes Andrew to her ranch to meet her father, who knows more about Parker's dealings. At the ranch, Andrew has his first encounter with the Maguires' unconventional pets, including their lion, Caeser, who gives him a fright. After growing accustomed to the lion's presence, Andrew eventually turns his attentions to Kathy and they spark a romance. Later, while Andrew visits the state capitol offices in Sacramento to investigate Parker's involvement in a questionable construction deal, Kathy, who has learned that Andrew was an orphan, enlists a group of children at the Oakport Orphanage to help with his campaign. When Andrew returns from Sacramento with evidence of Parker's corruption, he makes a secret deal with him to suppress the evidence in exchange for his unconditional support. Kathy and Andrew become engaged, but Kathy breaks off the engagement when Tim tells her about Andrew's secret deal with Parker. The break-up forces Andrew to realize his errors and, during a live radio show, he publicly reveals his deal with Parker. Andrew leaves the studio unaware that Herman, a dangerous lion, has escaped from the zoo and is roaming the streets of Oakport. While driving through town, Andrew sees the lion and, believing that it is Caesar, fearlessly prods him into his car. Kathy eventually finds Andrew, and he faints when she tells him that he has befriended a killer lion. Kathy revives Andrew and gives him a big kiss to show her admiration for his bravery in exposing Parker.