We are introduced to the life of the very young Buddhist apprentice living with his master on a small floating monastery, drifting on a lake in the serene forested mountains of Korea. The apprentice and his master live a life of prayer and meditation, using an old rowboat to reach the bank of the lake where they regularly go walking, for exercise and to collect herbs.
One day, in a creek among the rocky hills, the apprentice torments a fish by tying a small stone to it with string and laughing as it struggles to swim. Shortly after, he does the same to a frog and a snake; his master quietly observes on all three occasions, and that night ties a large, smooth rock to the apprentice as he sleeps. In the morning, he tells his apprentice that he cannot take off the rock until he unties the creatures he tormented—adding that if any of them have died, he will “carry the stone in his heart forever.” The boy struggles with the load on his back through the forest, and finds the fish lying dead at the bottom of the creek, the frog still alive and struggling where he left it, and the snake in a pool of blood, presumably attacked and killed by another animal, unable to get away. The master watches as the boy begins to cry heavily at seeing what he has done to the snake.
The apprentice (now in his teenage years) encounters a mother and daughter (dressed in modern clothes, indicating that the film takes place in modern times) walking along the forest path, looking for the monastery. The apprentice silently greets them and rows them across the lake to the monastery, where a colorful rooster is now part of the household. In Buddhist art, this bird is the representation of desire and craving. The daughter has an unspecified illness (she displays symptoms of a fever) and has been brought to the Buddhist master by her mother, hoping that she will be healed. The master agrees to take in the teenage girl for a time, and the mother leaves. Over the next few days, the apprentice finds himself sexually attracted to the girl, but is too shy to say anything; however, when he finds her sleeping in front of the Buddha statue, he is unable to resist groping her breast. She wakes up and slaps him. In a guilty panic, the apprentice begins to pray incessantly, something his master notes as strange. Touching the apprentice’s shoulder, the girl seems to forgive him.
Eventually, the two wander off into the forest and have sex. They repeat the act over the next few nights, hiding their relationship from the master, until he discovers them asleep and naked, drifting around the lake in the rowboat. He wakes them up by pulling the plug out of a drain hole in the boat. Rather than expressing anger or disappointment, he merely warns his apprentice that “lust leads to desire for possession, and possession leads to murder” and tells him that the girl will have to leave. The apprentice is distraught and runs away at night in pursuit of the girl, taking the monastery’s Buddha statue and the rooster with him. The implications of his two thefts are that while he is burdened with his craving as symbolized by the bird, he also has with him the “burden” of his master’s teachings as symbolized by the Buddha statue.
Many years later, during the fall, the aging master returns from a supply run to the local village, bringing a cat in his backpack. In East Asia, the cat is often seen in art as the cosseted pet of courtesans (e.g., in ukiyo-e prints) and is, therefore, often taken as signifying lasciviousness. However in Korean folkloric belief, the cat can be the expeller of evil spirits.
By chance the master glimpses a story about his former apprentice in a newspaper: He is wanted for the murder of his wife. Foreseeing the apprentice’s return, he modifies the teenage monk’s garments by hand, and soon afterward the adult apprentice appears in the spiritual door at the lake’s edge, full of anger and carrying the bloodstained knife with which he stabbed his wife for having an affair with another man. Unwilling to go on, he seals his eyes, mouth and nose in a suicide ritual and sits in front of the newly returned Buddha statue, waiting for death. The master discovers him and beats him ruthlessly, declaring that while he may have killed his wife, he will not kill himself so easily. He ties his bloodied apprentice to the ceiling and sets a candle to slowly burn through the rope, then begins writing out the “Heart Sutra” on the monastery deck, holding the cat in his arms and dipping its tail into a bowl of black ink. The apprentice eventually falls and, beginning his repentance, cuts his hair off and is ordered to carve the Chinese characters into the wood to quiet his heart.
Two detectives arrive at the monastery to arrest the apprentice, but the master asks them to allow him until the next day to finish his task. The apprentice continues throughout the night and collapses into sleep immediately upon finishing. Influenced by the soothing presence of the master, the detectives help the old monk paint his apprentice’s carvings in orange, green, blue and purple. This appears to quiet their hearts as well.
The apprentice wakes up and is peacefully taken away by the detectives, with the cat accompanying them in the back of the boat. After they leave, the master, knowing that his life is at its end, builds a pyre in the rowboat. He seals shut his ears, eyes, nose and mouth with paper in the same death ritual his apprentice performed and meditates as he is suffocated and burned to death. The master’s tears can be seen through the paper seals as he is engulfed in flame and a snake swims from the rowboat to the monastery.
Paroled, the now middle-age apprentice returns to the frozen lake and to his former home, which has been drifting uninhabited for years. During this segment the animal motif is the snake, the Buddhist symbol of anger. He finds his master’s clothes, laid out just before his death, and digs his master’s teeth out of the frozen rowboat. He carves a statue of the Buddha out of ice, wraps his master’s “sarira” (small crystals sometimes found among cremated remains of monks and regarded as sacred relics) in red cloth, and sets them in the statue where the “third eye” would be located, under a waterfall. He finds a book of choreographic meditative stances and begins to train and exercise in the freezing weather.
Eventually, a woman comes to the monastery with her baby son and a shawl wrapped around her face. She leaves her son and flees into the night, but as she runs across the frozen lake she accidentally stumbles into a hole in the ice dug by the monk. He finds her body the next day, and he removes her from the water to look at her face, although it is not shown to viewers. Instead, in the next shot, the scarf is open on the ice, and a carved stone head of Buddha is sitting on it.
Finally completing his long self-discipline, he ties the monastery’s large, circular grinding stone to his body. It is emblematic of the Buddhist Bhavacakra, the wheel of life and rebirth. He takes a statue of the Buddha-to-come, Maitreya, from the monastery and climbs to the summit of the tallest of the surrounding mountains. As he climbs, dragging the stone wheel behind him and struggling to carry the statue, he reflects upon the fish, the frog, and the snake he tormented. Attaining the summit, he prays and leaves the statue seated on top of the circular grinding stone, overlooking the monastery in the lake far below.
Returning to spring again, the cycle recommences: The new master lives in the monastery with the abandoned baby, now his apprentice. The boy is shown tormenting a turtle, ominously a traditional symbol of longevity and prognosticating the future. Wandering into the rocky hills, the boy echoes his predecessor, forcing stones into the mouths of a fish, frog and snake (these last scenes were deleted in the U.S. release of the movie).