In the Gamma Quadrant, Dax and Odo detect an unusual particle field on the surface of an unexplored planet. Transporting to the source, they find an alien village and some kind of reactor emitting the particle field. They are then taken prisoner by Colyus, Protector of an Yaderan colony which settled in a valley there. He explains that Dax and Odo's arrival coincides with the mysterious disappearances of 22 people. Odo and Dax are sympathetic to Colyus's plight and offer their help in solving the mystery. They meet Rurigan, an elderly man whose daughter is the most recent victim, and Odo questions Rurigan's young granddaughter, Taya, the last person to see her mother before she vanished.
The next day, Odo tries to establish a rapport with the shy Taya, and she opens up to him and talks about her life and her mother. Odo is surprised when she explains that the Yaderans never leave their valley, and reveals Rurigan thinks her mother will never return, but Odo vows to bring back the missing woman.
Odo learns from Rurigan that he is one of the founding members of the village, the oldest one remaining, and that he is dying. He also assures Odo that searching away from the valley for the missing people would be futile. Still, Odo is determined to investigate, and goes with Dax and Taya to the edge of the valley. As Dax and Odo pass some bushes, the Yaderan sensing device Dax is carrying disappears. Then Taya reaches past the bushes, but her arm disappears up to the elbow, then rematerializes as she pulls it back closer to her face.
After some investigation, Dax and Odo share their surprising findings with Colyus. The entire village, including all the people, is an elaborate holographic projection, created by the village reactor that generates the particle field. The reactor is breaking down, causing people to disappear. After the villagers see this for themselves, Colyus convinces them that — real or not — if they are to survive, Dax and Odo must be allowed to shut down the reactor and repair it before it experiences a complete failure. Dax proceeds, and the village vanishes, leaving Dax and Odo standing — with a very real Rurigan.
Rurigan explains that when the Dominion took over Yadera Prime and destroyed his life, he came to this planet and used a holo-generator to recreate the world he had lost. Realizing his illusion may be forever gone, Rurigan reluctantly asks to be taken back to his homeworld. But Dax and Odo have a different view of the situation. They show Rurigan that, if the Yaderans are real enough for him to develop feelings, they are real enough to deserve a chance at survival. Dax and Rurigan repair the reactor, and the entire society reappears, including his missing daughter and the rest of the people who vanished.