Sam wakes up confused about the time after falling asleep in the armchair in his apartment. He had been dreaming of his mother singing the Sandman song to him as a three-year-old in 1973.
When he leaves to take a walk in the neighborhood, he passes a little girl on a tricycle who is singing the Sandman song his mother had been singing. He realizes she is the same little girl whose picture he had found in the shoebox earlier. As she rides away, he sees a man forcing a woman into his Cadillac. The man orders Sam to leave, but Sam takes him down and arrests him. He then takes a good look at the woman - it is his mother, Rose Tyler.
Sam takes Rose and the gangster, Sam Profaci, back to the 125th only to find that Rose doesn't want to press charges. In addition, Sam's fellow officers are surprised that he had arrested Profaci in the first place. He asks Annie to look after Rose, and goes to Hunt's office, where Gene and Ray are sharing whiskey and jokes with the man. As Sam stares in disbelief, Annie enters the room to tell him that Rose has left the station.
As Ray escorts Profaci out of the station, it is clear to Sam that Profaci is Ray's bookie. Hunt explains that Profaci works for a gangster, Elliot Casso, who gives them tips about crimes in exchange for the freedom to run his bookmaking operations without police interference. Annie pulls Sam aside and tells him that Profaci had been a suspect in the murders of two women who had been pulled from the East River. Ray didn't investigate the cases, however, although one of the women had left a young son.
Annie gives Rose's address to Sam and pays her a visit. When he enters the apartment, he introduced himself as Luke Skywalker. He sees photos of himself as a child with his father and mother, and is overwhelmed by old memories. Rose explains why Profaci had been strong-arming her. Her husband is a traveling salesman and they were short of cash. She had taken money from a loan shark who worked for Profaci. After she finishes her story, her son, Sammy, wakes up from his nap in the other room, so Sam leaves before meeting his past self fearing the consequences.
Hunt takes Sam to Club Vendetta to apologize to Profaci and Elliot Casso. Casso also makes Profaci apologize. Sam accepts the apology on the condition that he leaves Rose Tyler alone. Casso introduces the men to two prostitutes in the office, Adrienne and Jilly. While Hunt and his men are entertained by the two women, Profaci offers a roll of cash to Sam. Sam refuses the bribe. Now suspicious of Sam, Profaci and Casso are determined to figure out the connection between Sam and Rose Tyler.
Sam pays a visit to Rose the next day to check on her, and she tells him through the partially open door that the day before she had had three weeks to pay back Profaci, but now she only has three days. Sam promises her everything will be all right, and notices a red dress Rose is carrying in a dry-cleaning bag.
Sam confides to Annie later that he remembers his mother wearing that red dress. Annie dismisses his obsession with Rose, but Sam insists the reason he is in 1973 might be to help his mother. Annie suggests if he wants to help Rose Tyler, he will find the evidence to arrest Casso and Profaci for the two homicides.
Back at his apartment, Sam receives a visit from Adrienne. She claims Profaci had beaten her and asks for Sam's help because she believes he is the only person who is not in Casso's pocket. He allows her to stay for the night. Adrienne tries to seduce Sam, but an uncomfortable Sam receives a call from Annie reminding him that he had a date that night to see a movie. Sam apologizes to Annie, says goodnight to Adrienne who has settled on his bed, then goes to sleep in his armchair.
Once asleep, Sam has a disturbing dream in which his mother, wearing her red dress, is dancing with Lt. Hunt. He visualizes violent images of the time period. He dreams of having sex with Adrienne, who changes into Annie, who changes into Rose Tyler, who changes into Windy, who changes back to Adrienne. Sam is awakened from his dream when Ray kicks in his door. Sam is lying naked on his bed with his wrists and ankles are handcuffed to the bed rails. Ray tells Sam that Adrienne probably dosed him with LSD and most likely took some incriminating photographs. Annie had followed Ray into the apartment, and makes a humorous comment about "seeing" Sam this way for the first time.
An angry Sam goes to Club Vendetta to retrieve the photographs. When he enters Casso's office, he sees Adrienne and she appears to feel remorse at what she had done. Hunt enters the room along with Casso and Profaci. Casso shows Sam the photos, and tells him that if he steps out of line, the photos will be printed in the papers. Hunt again tries to get Sam to leave Casso alone, even threatening to publish the photos himself.
Later that day, Sam knocks on Rose's door and hands her an envelope full of money and begs her to leave town with her son. As they stand at the door, he catches a glimpse of Sammy, who is actually himself at three years old, and is unable to hear anything but his own heartbeat and breathing. Rose brings Sam into focus by asking the boy to leave. She tells Sam that she has worked everything out with Profaci and shuts the door in Sam's face.
Sam finds an envelope from Adrienne that had been slipped under his door that contains the negatives of the photographs and a written apology. Sam had indeed made her feel guilty and she wants to make things right. In the note, she tells Sam he can find all the evidence he needs in Casso's credenza. Later that night, Chris informs Sam another body has been pulled from the river - the body of Adrienne.
In a moment of camaraderie, Hunt tells Sam the story of his first partner who had ratted out some corrupt cops, but had become so despised among his peers that he had committed suicide. Hunt believes he might have been a part of the problem, and it made him feel as though there was an animal eating away at his insides.
On hearing this story, Sam enlists Hunt's help in taking down Casso and Profaci. The two detectives raid Club Vendetta. Sam goes for the credenza, where he finds a case filled with heroin. As they arrest Casso and Profaci, Sam sees Rose in the office and wearing the red dress. She had just begun her first night working at the club to pay off her debt. Sam tells her she can go home and kiss her son goodnight.
After the arrest, Hunt and Sam walk into the squad room, expecting to be ridiculed by their fellow officers. Instead, the men are greeted with cheers and pats on the back. The officers of the 125 are in high spirits to be unburdened by Casso and Profaci.
Later that night, Hunt opens the trunk of his car to reveal a grocery bag filled with money he had received from Casso over the years. Reluctantly, he throws one roll of cash into a flaming trash can. As he throws each roll of money into the can, the weight of his guilt is lifted slowly from his shoulders.
Rose walks into her son's bedroom to tuck him in. She is wearing the red dress and she is crying. She tells young Sammy that she loves him very much. A smiling Sammy asks his mother to sing the Sandman song to him.