Haruhiko's family travel around Japan putting on puppet shows. They never stay anywhere for longer than a month, so Haruhiko has no time to make friends. While staying in one town he becomes friendly with a girl called Kinuko, and takes her to see his family's puppets. She is frightened by "Jean-Pierre", a creepy-looking puppet that belongs to his brother Yukihiko. Shortly after, the family has to leave town, but Kinuko promises that she will see Haruhiko again.
Haruhiko's father gets sick and the family has to move into an apartment. Their father talks about how he loves being a puppeteer because he controls the puppets completely. While alone with Haruhiko, Yukihiko says he's always thought that it was the other way around: their father was doing whatever the puppets wanted. He runs away from home that night. Their father soon dies, and Haruhiko and his sister Natsumi go to live with a cousin, eventually getting their own place when Haruhiko is in high school.
Haruhiko meets Kinuko again and she becomes his girlfriend. One day they receive a letter from Yukihiko. He is now living in the same town and invites them to visit him. He is extremely rich and owns his own company, but he and his family are suspended from piano wire that is controlled from the ceiling by hired puppeteers. Haruhiko is very disturbed, but Yukihiko says that the puppet is the one in charge of the puppeteer. Yukihiko still has Jean-Pierre, and he owns a set of life-sized ballet dancer puppets designed to entertain people.
Haruhiko doesn't want to visit again, but Natsumi loves Yukihiko's house, and they begin to visit regularly. She wants to become a "puppet" herself and dance like the ballet puppets. She dresses up and is controlled by the puppeteers to dance beautifully like the dolls. Haruhiko is upset that Yukihiko and his family have never taken the strings off in two years, and even more upset when Natsumi refuses to take off her costume and go home. He is forced to let Natsumi live with Yukihiko, but refuses to move in himself. He doesn't want Kinuko to meet Yukihiko and has to make excuses for his visits to Yukihiko's house.
When Haruhiko visits the house one day, the ballet puppets lead him into a room and try to get him to put on strings. Kinuko has followed him and is watching from the street. She mistakes one of the puppets for a real woman and thinks Haruhiko is cheating on her. Suddenly, Jean-Pierre arrives and lures her into the house. Inside, the puppets have begun to dance wildly, including Yukihiko and his family. Yukihiko screams that Jean-Pierre is out of control, causing Haruhiko to realize that Jean-Pierre has been manipulating Yukihiko's mind the whole time. Haruhiko goes up into the roof and finds that the puppeteers are in a trance-like state and being controlled by Jean-Pierre.
Haruhiko chases after Jean-Pierre and discovers the body of Kinuko, whom Jean-Pierre has violently slashed to death and suspended from the ceiling. Haruhiko screams "Why? Why?" and destroys Jean-Pierre with the knife. He rescues Natsumi, but Yukihiko and his family are no longer human; they are marionettes made of wood. Haruhiko thinks that maybe they were always that way, he just didn't notice.