The Enterprise is docked at Deep Space Nine, providing assistance in repairing the station. Julian Bashir, DS9's Chief Medical Officer, has come aboard to get assistance in examining a piece of technology that was found in the Gamma Quadrant and is working with Geordi and Data. During a conversation, Bashir notices that Data breathes, and so Data explains some aspects of his design that make him look more like a human.
But the main focus of the episode is on Worf, whose story will completely fill Part II. In cafe on DS9 Worf is approached by an alien, Jaglom Shrek (played by James Cromwell), who claims that Mogh, Worf's father, was not killed at Khitomer, but instead was captured by the Romulans. Since Mogh's capture would dishonor Worf and his own son, Worf at first refuses to believe the alien's claim but it upsets him.
Meanwhile, Data, Geordi, and Bashir are working in engineering with the piece of equipment Julian brought over. During a test there is a sudden energy discharge which hits Data, causing him to collapse on to the deck. Data has a dream-like experience in which he wanders through one of the ship's corridors. He sees a bird and hears the sound of a hammer on an anvil. He finds the person banging the hammer and it is his "father", creator Noonien Soong. Before he can learn any more he is revived by Geordi.
Data is puzzled as to what happened. Bashir suggests that maybe he had a dream. Data approaches Worf, asking about the time Worf had a hallucination during a Klingon ritual. Worf says that it is important for Data to find the dream's meaning, and on learning that Data's dream involved Data's creator, Worf says that "Your father is a part of you, always." This causes Worf to resolve himself to find out the truth about his father.
Worf goes back to DS9 and hunts down the alien. He demands the alien to take him to the Romulan prison camp. The alien refuses. Worf grabs him and dangles over a high bridge. The alien doesn't wish to go because the camp is on a planet on the fringe of Romulan space. Worf threatens the alien. After getting a leave of absence from the Enterprise, he sets off with the alien to the planet in question. On arrival the alien takes him to a clifftop from where they can see the camp.
Back on the Enterprise Data visits Picard. Data tells Picard that he is investigating the dream, but has reached no conclusion. Data claims he has no culture, so he has turned to others for meaning. Picard fundamentally disagrees, informing Data, "You are a culture of one which is no less valid than a culture of oneï»¿ billion." He tells the android to turn to within himself to find the meaning of the dream. Data goes to his quarters to paint images related to his dream.
On the planet, Worf and the alien delve into the dark jungle. Worf moves towards the compound. He spies a female bathing in the wilderness. Worf pursues her and finds out she's a Klingon. The Klingon female goes back to the compound.
Geordi stops by Data's quarters, where in addition to dream-related paintings, Data painted a bird but can't explain why. He asks Geordi to help him recreate the experiment that caused the dream. Geordi reluctantly agrees, warning Data that it could fuse his brain. Bashir and Geordi initiate the experiment. Data is zapped again and has another vision. It begins the same as the first: Corridor, sound of a hammer, Soong. Soong plunges a bird's wing into a bucket of water, causing steam to billow out. When the steam clears, Soong is gone and a bird is left in his place. Data realizes that the vision is different, saying so out loud. Soong appears to him, saying that of course the dream is different. Data is now on the bridge. Data begins to relate all the things that are different: The bridge is there, his cat Spot, his potted plant, and his paintings. Soong says Data is showing progress. Data doesn't understand. Soong says that is all right. Awake, Data believes that the dream was pre-programmed by Soong. He also plans to "sleep" for a brief period every day, to "dream". Bashir asks if he could write a paper on this event, and Data approves.
Worf breaks in to the prison compound and hears singing. A Klingon male warns Worf that there are things going on that Worf doesn't understand. The Klingon says he remembers Worf as a child, and relates a story about how Worf injured himself as a child while on a hunt. Worf says he remembers the old Klingon, who warns him that he should not have come here. The Klingon elders grab Worf, attempting to keep him in the compound. He easily defeats them and begins to run, only to be stopped by two armed Romulans.