After returning home from Paris, Gwen is trying to leave for work but Gwen insists on pulling her back into bed. She resists, and admits that having him to come home to is the best part of her work.
At the Hub, Jack gets out a box of unlabelled Class D artifacts and has Tosh, Owen, and Adam Smith check their providence. Adam admits that he's been okay doing the background audits for the last three years. Gwen comes in and has no idea who Adam is. As everyone else stares in surprise, Adam touches Gwen and she suddenly has a complete set of memories of him having been a team member since she joined the organization.
Once he's alone, Adam updates his computer records, and then reprograms Tosh's memories so that she thinks they've been involved for the last year. Tosh notices Owen watching them and asks if he's okay, and he admits he's surprised to see them kissing at work. Meanwhile, Adam goes to the cells below and has a brief vision of a young boy in one of the holding cages. Gwen comes in and asks if Jack missed her, and the two flirt.
Ion the Hub, Tosh notices that there was rift activity two days ago but nothing apparently came through. A rather nerdy Owen offers her a screen cleaner and she turns it down, and Gwen and Ianto note that he's never realized that he doesn't have a chance with Tosh. Adam tells them to leave Owen alone.
Gwen returns home and finds Rhys in her apartment. She has no idea who he is and grabs first a knife and then a gun. She calls Jack to tell her someone has broken in and used a key. Jack and Adam arrive and Jack knows who Rhys is and that he's been with Gwen for years. Rhys points out she's wearing his engagement ring and Adam suggests she come to the Hub for a checkup. As she leaves, she tells them that if Rhys comes after her again, she'll kill him. Jack promises Rhys that they'll put things right.
Owen examines Gwen but can't find anything wrong. Meanwhile, Jack has Rhys record everything about how he and Gwen have been together and transmits it to Gwen. She vaguely remembers what he's saying but can't connect to it emotionally. Adam reassures her that it's just his memory playing tricks and that the memories are there somewhere.
Tosh and Owen examine the artifacts and Owen I uncomfortable being around her. They settle in for a long night and he brings her a sandwich. She's surprised that he knows what her favorite satellite is, and then goes to get a beer. He's surprised that she's drinking.
Ianto brings Gwen back to her flat and he and Jack leave her alone with Rhys. Outside, Jack sees the same boy from earlier but Ianto has no idea who he's talking about. Jack dismisses it as his imagination and prepares to leave top investigate a Weevil sighting. When Ianto suggests he go with him, Jack abruptly tells him he'll handle it alone.
Tosh brings Owen a beer and tells him to live it up and celebrate her one-year anniversary with Adam. She talks about how it was love at first sight and assures Owen he'll meet the right girl some day. They go back to work.
Jack goes into the sewers after the Weevil but finds himself face-to-face with an older man. Jack recognizes the man as his father, who tells him to get out. Jack runs out into the open and turns to find Adam waiting for him. Jack wonders how he got there and Adam says he came with him, and then touches him to implant the memory confirming it. He asks what Jack saw, and Jack tells hi he saw his past.
At her flat, Gwen still has no memory of being with Rhys and wonders how she could forget their relationship. He tells her how he was going to go out to get them something to eat but didn’t want the weekend to end.
Adam tries to find out what Jack was remembering and continues to use his ability to reinforce Jack's memories that he can be trusted. Jack admits he buried the memory over 150 years ago and it's coming out, and says that he can't afford to remember what happened. Adam persists and Jack finally says he's on a beach on the Boeshane Peninsula in the 51st century. As a young boy, invaders came and his father told Jack to hide with his younger brother Gray. However, Jack lost him in the chaos and went home to find him . Instead he found his father, dead. After that, he searched for Gray for years but never found him. Jack blames himself and insists it's the last thing he wants to remember.
Tosh and Owen continue their analysis of one artefact, a wooden box, and Ianto suggests that Jack brought it. Tosh believes it was Adam. Ianto goes to check his diary and Owen notes that she's nervous that Adam hasn't called her yet for their anniversary. He tells her that he'd cherish her if they had an anniversary and says that he loves her. Surprised, he admits that he already has and insists on telling her about his feelings. She tells him that it was inappropriate and says that Owen would never be her type.
Rhys and Gwen go shopping and she suggests she should be on her own. As he snaps at the cashier, Gwen starts to remember him and he takes her out.
Ianto goes through his diary and can't find any mention of Adam. Adam appears next to him and Ianto wonders who he is. As he speaks, Adam's hand briefly disappears and then reappears. Adam then feed him with memories of how Ianto goes out and kills women, and then calls Adam to help dispose of the bodies. As he talks, he boasts of the rush of feeding on the bad stuff.
Jack remembers more of his childhood, going back to find his mother crying over his father's corpse and then asking Jack where Gray is. Jack tries to figure out why he's having the memories now.
A nervous Gwen gets into bed, all but fully dressed, and admits she's starting to remember him. She insists that they found it before and will find it again, and Rhys admits that he always worried that she just settled for him. He wonders if she'd give him a second thought now that she's joined Torchwood and then kisses her. She doesn't remember and says it felt like the first time, and admits that it was nice. She tells Rhys to remind her some more.
Adam goes back to Tosh to her apartment. As they make love, he asks her how far she would go for him, and if she would die for him. Tosh says that she would
Jack returns to the Hub and finds Ianto crouched in a corner. Ianto tells Jack to lock him up because he killed three girls. Jack doesn't believe it but Ianto insists he murdered the girls in cold blood and disposed of the bodies. Jack doesn't believe it and wonders what happened to him, and then embraces him. He uses a lie detector and has Ianto repeat his story. Jack confirms that it's true but refuses to believe it. He goes over the internal tapes and finds Adam feeding Ianto new memories. Going further, he discovers all the other times that Adam programmed everyone with the memories he wanted. He shows Ianto the footage and then brings up Adam's files. They realise the file was brought up 24 hours ago.
Owen comes in with flowers for Tosh and Jack and Ianto hastily cover up their investigation. Tosh and Adam come in and Owen apologises for his outburst earlier. He insists the most important thing is that she's happy, and asks if she's happy with Adam. She tells him that she is.
Gwen comes in and Adam assures her they'll look after her. Jack draws a gun and points it at Adam's head, and explains to the others that he's been feeding himself into their memories by touch. As he takes Adam to the vaults, Tosh draws her gun but Ianto disarms her.
In the cell, Adam explains that he had to become part of their memories in order to survive. He insists he's helped them all. Tosh is more confident, Owen is no longer a cynic. Jack's memories drew him there and Adam reminds him that he always remembers what he killed.
Jack hypnotizes the team and tries to get them to go back and remember what they are. The team remembers their most important memories, good and bad. Gwen notes that she loves Jack, but in a different way than Rhys. He gives them retcon pills to induce short term amnesia and make them forget Adam and go back to who they were. Ianto and Gwen take the pills. Owen looks thoughtfully at Tosh before taking his. Tosh brings up the image of Adam and says that she'll lose so much, but Jack says that Adam forced it on her. She finally takes it and says goodbye to Adam. Once she takes it, they all pass out.
Jack goes to see Adam and inform him he's the last one. Adam reminds him that he'll keep the bad memories, but asks about the last good memory of him and his dad. He offers to take Jack back and remember it. When Jack wonders why Adam would do that, Adam explains that he was in the void so long that Jack gave him color and life, and he wants to help him. Jack agrees and he remembers the last time he, Gray, and their father were together and happy. However, he remembers a new person there: Adam, trying to insert himself into Jack's memories and turning his father against him. He explains that the artefact they found contains his last memory. Now that he's in Jack's memory of the past, he'll always live on. Jack prepares to take the retcon pill and Adam warns that he'll lose all his memories of his father. Jack tells him goodbye and takes the pill. As Jack forgets his father, Adam collapses in pain and then disappears.
Later, Jack and the others recover consciousness with no memory of the last 48 hours. All of the recordings have been wiped and Jack admits he doesn't know what happened. He points out the flowers and apology note that Owen left Tosh, but Owen dismisses it as a joke and says he doesn't do apologies.
Jack examines the artifact and a piece drops out of it. Ianto comes in and Jack gives him his diary back. As Ianto goes, Jack finds Adam's name on a plastic evidence bag but Ianto has no idea who it is. Jack then inserts the piece into the box and it opens. Inside there is nothing but dust.