We open on Sam dreaming of his mother singing the Sandman song to him as a 3 year-old in 1973. Sam has fallen asleep in his apartment chair and wakes up confused about his time warp. He takes a walk in the neighborhood, and passes a little black girl who sings the Sandman song. He realizes it's the same girl whose picture he found in the shoebox in the previous episode: yet another bizarre coincidence in his new reality. As she bikes away, he witnesses a gangster, Nick Profaci, trying to force a woman into his Cadillac. Profaci tells Sam to hit the bricks, but Sam takes him down and arrests him. As he does, he looks up at the woman -- only to realize it's his mother, Rose Tyler!
Sam takes Rose and Profaci back to the 125th only to find that Rose doesn't want to press charges. On top of that, Sam's co-workers are surprised he arrested Profaci. Lieutenant Hunt and Ray even share some whiskey and laughs with the man in Hunt's office. As Sam expresses his disbelief, Annie walks in to tell him that Rose has left the station.
As Ray escorts Profaci out of the station, it's clear Profaci is Ray's bookie. Hunt explains to Sam that Profaci works for a gangster, Elliot Casso, who gives them tips about crimes in exchange for the freedom to run his own operations without harassment. Annie tells Sam the other side of the equation: Profaci is a suspect in the murders of two women found dead in the East River. However, Ray didn't investigate the cases, even though one of the women left a young son behind.
Sam finds Rose Tyler's address and pays a visit. The déjà vu of visiting his old home overwhelms him. He sees photos of himself as a child with his parents. Rose explains her situation. Her husband is a traveling salesman, she was in need of a loan, and she took money from a loan shark working for Profaci. They hear her son Sammy wake up from a nap in the other room, and Sam feels compelled to leave before seeing him(self).
Dragging Sam to Club Vendetta, Hunt forces Sam to apologize to Profaci and Casso for his actions. Casso also makes Profaci apologize and Sam accepts with the condition he leaves Rose Tyler alone. Casso introduces the men to two prostitutes working for them, Adrienne and Jilly. While Hunt and his men have a good time with the girls, Profaci approaches Sam with a wad of cash, hoping it will help bygones be bygones. Sam is insulted and refuses the bribe. Now suspicious of Sam, Profaci and Casso decide to figure out Sam's connection with Rose Tyler.
The next day, Sam approaches Rose, who tells him that the day before she had three weeks to pay Profaci back, but now she only has three days. Sam promises her everything will be okay and notices a red dress Rose is carrying in a dry-cleaning package. Sam confides to Annie that he remembers his mother wearing that red dress. Annie dismisses his obsession with Rose as an Oedipal issue, but Sam insists part of his mission in 1973 might be to help his mother out. Annie suggests if he wants to help her, he'll nail Casso and Profaci on the homicides.
Back at his apartment, Sam receives a visit from Adrienne from the club. She claims Profaci had beaten her and asks for Sam's help, since he's the only one not in Casso's pocket. He allows her to crash at his place for the night. Adrienne tries to seduce Sam, but they're interrupted when Annie calls, reminding Sam he had a date with her to see a movie. Sam apologizes then gets out of sleeping with Adrienne by insisting on sleeping in his chair.
Once asleep, Sam has a disturbing dream in which his mother, in her red dress, tangos with Lt. Hunt. He visualizes violent images of the time. He dreams of making love to Adrienne, who morphs into Annie, then into Rose Tyler, then Windy, then Adrienne again. Sam is suddenly awakened when Ray kicks in his door. Sam is naked, wrists and ankles handcuffed to the bed. Ray explains that Adrienne probably dosed him with LSD and took incriminating photos of him.
Angered, Sam heads to Club Vendetta to retrieve the photos. He sees Adrienne and makes her feel ashamed for her actions. Hunt walks in with Casso and Profaci. Casso shows Sam the photos, telling him 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 use the photos himself.
Sam gives Rose an envelope full of money and begs her to leave town with her son. As he does, he catches a glimpse of her son -- himself at three years old -- and finds himself unable to hear anything but his heartbeat and breathing. Rose shoos the boy away, breaking Sam's trance. She claims she worked everything out with Profaci and closes the door in Sam's face.
Sam receives an envelope from Adrienne containing the photo negatives and a written apology; Sam succeeded in making 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.
That night, Chris informs Sam another body has been pulled from the river. It turns out to be Adrienne. Ray argues with Sam over whose fault her murder is, but Hunt breaks them up when they see Adrienne's weeping mother at the scene.
Hunt sadly recounts to Sam the story of his first partner who ratted on some corrupt cops but became so hated among his peers that he committed suicide. Hunt may have been a part of the problem, but when something like this happens, he feels "like there's an animal eating away at my insides."
Sensing an opening, 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 satchel full of heroin. As they arrest Casso and Profaci, Sam catches a glimpse of Rose, wearing the red dress. She just began 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 125th squad room, expecting to be hated by their co-workers. Instead, the men are greeted with cheers and pats on the back; the cops of the 125th are happy to be unburdened by the rats Casso and Profaci.
That night, Hunt opens his trunk to reveal a grocery bag filled with years worth of wads of cash from Casso. He's never spent a penny of it. Reluctantly, he throws a wad of cash into a flaming garbage can. As he throws each successive wad into the can, he grows more eager. We see the weight of his guilt slowly lift off of his shoulders.
Meanwhile, Rose Tyler, still in her red dress, walks into her son's bedroom to tuck him in. She's still in tears, unable to hold back her emotions, and tells young Sammy she loves him very much. Sammy, in turn, asks Rose to sing him the Sandman song.