- Kim Ki-taek, an unemployed driver, lives with his wife Chung-sook, son Ki-woo and daughter Ki-jeong in a shabby semi-basement apartment. The family struggle to survive, working low-paying gigs, such as folding pizza boxes. Ki-woo's friend Min-hyuk visits the family and gives them a large rock supposed to bring them wealth before he leaves to study abroad. He suggests Ki-woo take over his job as an English tutor for the wealthy Park family's youngest daughter, Da-hye. In the lavish Park mansion, Ki-woo is interviewed by Mrs. Park to tutor Da-hye, and is hired after Mrs. Park sees his talents in action. Learning of Mrs. Park's struggle to find an art teacher for her younger child, Da-song, Ki-woo suggests a "professional" named Jessica, who in reality is Ki-jeong. Once hired, Ki-jeong leaves her underwear in Mr. Park's car to get his driver fired and replaced with her "uncle's former driver": Ki-taek. The Kims soon get housekeeper Moon-gwang fired after framing her peach allergy as tuberculosis. Now replaced by Choong-sook, the entire Kim family is employed by the Parks.
The Parks go on an overnight camping trip, leaving the mansion in Chung-sook's care. The Kims take the opportunity to have a drunken party in the mansion, during which Ki-woo confesses to his family that he is in love with Da-hye. In the middle of their celebration, Moon-gwang rings the bell and claims that she came to retrieve something from the basement. The other Kims hide, then Chung-sook lets Moon-gwang in. Heading to the basement, the former housekeeper opens a secret bunker, revealing that her husband, Geun-sae, has been hiding for four years to avoid loan sharks. As Chung-sook threatens to call the police, the rest of the Kims, eavesdropping, accidentally stumble into view. Moon-gwang quickly records footage of the new "staff" addressing each other as father and children, then threatens to send the clip to the Parks. Moon-gwang and Geun-sae then force the four to perform humiliating acts, until a fight erupts in the living room and Ki-woo wrestles the phone away and deletes the footage.
The Parks call Chung-sook to announce that the heavy rain has ruined their camping trip and they will be home soon needing dinner to be prepared. The Kims scramble to confine Moon-gwang and Geun-sae, then clean up and hide. Moon-gwang breaks free and runs up into the kitchen, but Chung-sook pushes her down the basement stairs, severely wounding her head. While eating, Mrs. Park tells Chung-sook that her son was traumatized one birthday by what he thought was a ghost coming up from the basement. After a few close calls, the other three Kims leave the mansion undetected. They run back to their apartment, which has been flooded by the storm. They salvage what they can, Ki-woo carrying the large "lucky rock" Min-Hyuk gave his family earlier. The three, along with other displaced citizens, sleep in a gymnasium. Meanwhile, Moon-gwang dies from her concussion as Geun-sae cries.
The following day, Mrs. Park throws a birthday party for Da-song and invites the Kims. During the party, Ki-woo carries the rock down to the bunker, intending to kill Geun-sae. Geun-sae ambushes Ki-woo, cracks his head open with the rock, then crashes the party, where he stabs Ki-jeong in the chest. Geun-sae's sudden appearance triggers Da-song's traumatic memory, causing the child to have a seizure. Ki-taek rushes to stop Ki-jeong's bleeding, while Mr. Park yells at him for the car keys, so Park can drive Da-song to the hospital. The key lands under the fighting Chung-sook and Geun-sae, before Chung-sook kills Geun-sae with a meat skewer. Mr. Park retrieves the key, while recoiling from Geun-sae's "poor man's smell." Ki-taek, witnessing Mr. Park's reaction to the smell, also his own, snaps, fatally stabs him, then flees.
Ki-jeong and Mr. Park die from their wounds, while Ki-woo requires brain surgery and suffers a weeks-long coma; he and Chung-sook go to trial and are sentenced to probation. Later, watching the Parks' mansion, Ki-woo notices a light flickering in Morse code – a message from Ki-taek, who had managed to retreat into the bunker in the chaos, and has been hiding from and living off of the new owners. Ki-woo promises that one day, he will earn enough money to buy the house and free his father. Fantasizing about the day of their reunion, the film ends with Ki-woo in the semi-basement where he began.
Bong Joon Ho
Song Kang Ho
Lee Sun Kyun
Cho Yeo Jeong
Choi Woo Shik
Park So Dam