The Kim family—father Ki-taek, mother Chung-sook, daughter Ki-jung, and son Ki-woo—live in a small semi-basement apartment (banjiha) in Seoul, where they work low-paying temporary jobs folding pizza boxes. Min-hyuk, a university student and Ki-buddy, woo’s presents the family with a scholar’s rock, which is said to bring wealth. As he prepares to study overseas, Ki-woo advises that he disguise himself as a university student and take up his work as an English instructor for Da-hye, the wealthy Park family’s daughter. Ki-woo is later hired by the Parks after posing as a Yonsei University student.
The Kim family devises a plot to secure employment for each member of the family by acting as unrelated and highly qualified individuals in order to serve the Parks as servants. Ki-jung impersonates “Jessica” and works as an art therapist for the Parks’ young son, Da-song, using Ki-Woo as a model. Mr Park’s chauffeur, Yoon, is framed by Ki-jung by making it appear as if he had sex in the car, and Ki-taek is recommended to take his position. Finally, Chung-sook takes over as the Parks’ housekeeper after the Kims utilize Mrs Park’s long-time housekeeper, Moon-peach gwang’s allergy, to convince her that she has tuberculosis. Ki-woo and Da-hye begin a hidden romantic relationship.
When the Parks leave for a camping vacation, the Kims enjoy the amenities of their home until Moon-gwang knocks at the door and informs Chung-sook that she has forgotten something in the basement. Moon-husband, gwang’s Geun-sae, has been hiding from loan sharks for almost four years, and she discovers a hidden entrance to an underground bunker established by the architect and previous homeowner. Moon-gwang begs Chung-sook to let Geun-sae stay in the bunker, but the eavesdropping Kims inadvertently betray themselves. Moon-gwang records them on her phone and threatens to tell the Parks about their deceit.
The Parks return home early owing to a violent thunderstorm, and the Kims race to clean up the house and tame Moon-gwang and Geun-sae before they arrive. Geun-sae and Moon-gwang are cornered in the bunker by the Kims. Mrs Park tells Chung-sook about Da-seizure-inducing song’s horrific experience on his previous birthday, when he saw a “ghost” — actually Geun-sae — emerge from the basement late at night. Before the Kims can get out of the house, they overhear Mr Park making snide remarks about Ki-odor. taek’s As a result of the violent downpour, the Kims’ flat is flooded with sewer water, forcing them to seek shelter in a gymnasium with other displaced persons.
Mrs Park, with the help of the Kim family, throws a house party for Da-birthday song’s the next day. To find Geun-sae, Ki-woo enters the bunker with the scholar’s rock. He is ambushed by a psychotic Geun-sae, who bludgeons his head with the rock and flees, leaving Ki-woo lying in a pool of blood at the entrance to the basement, having died from a concussion she got during the earlier struggle. Geun-sae stabs Ki-jung with a kitchen knife in front of the terrified party guests in order to avenge Moon-gwang. When Da-song sees Geun-sae, he has another seizure, and a battle ensues until Chung-sook fatally impales Geun-sae with a barbecue skewer. Mr Park tells Ki-taek to drive Da-song to the hospital while Ki-taek attends to a seriously bleeding Ki-jung. In the midst of the turmoil, Ki-taek angrily kills Geun-sae with the knife after witnessing Mr Park’s horrified reaction to Geun-odor. sae’s The remainder of the Kim family is left behind as Ki-taek escapes the scene.
Ki-woo is still recovering from brain surgery weeks later. He and Chung-sook were both found guilty of fraud and sentenced to probation. Ki-jung died as a result of her injuries, and Ki-taek, who was wanted by the police for Mr Park’s murder, has yet to be located. Geun-sae is thought to be a mentally ill homeless guy, and neither he nor Ki-motive taek’s for the stabbings has been revealed. Ki-woo notices a message in Morse code from a flickering light in the Parks’ home, which is now owned by a German family who is unaware of its history. Ki-taek, who got into the bunker through the garage, buried Moon-gwang in the backyard and now attacks the kitchen at night, hoping Ki-woo will receive the message. Ki-woo writes a letter to Ki-taek, still living with his mother in their original basement flat, promising to work hard enough to one day buy the house and reconnect with his father.