Eugene Jones finds himself lying in a road. He gets up and notices Torchwood investigating a hit-and-run site nearby. Eugene goes to check it out but they ignore him and examine a body. Gwen wonders why the victim was there. He moves forward and discovers the body is his. He reaches for Gwen and his hand goes through her.
Off to the side, Eugene's phone rings. His mother is calling and Gwen says they need to talk. As the team moves out, Eugene gets in the vehicle with them. Eugene tries to remember everything that has lead up to this point but can't remember the last few weeks. However, he remembers the rest of his life. In school he participated in the Interschool Math Competition in 1992 but blanked. Everyone blamed Eugene for losing. and afterward, his teacher Mr Garrett shows him an eye that he claims dropped out of the sky. Garrett gives it to Eugene. Eugene's father Shaun comes in to take him home. Eugene was fascinated by the eye, which made him think everything was okay even after his father left for good. The boy figured that an alien would come back and claim its eye, and used his mathematical abilities to compute where it might come from.
As Eugene became older, he became ever more fascinated with watching the skies and collecting alien artifacts. He met Gwen at a site during a Torchwood investigation and tried to show her his notes, but she never took interest of him.
Gwen goes to tell Mrs. Jones and his brother Terry about Eugene's death. The team goes through his room and finds his collection of items. Mrs. Jones asks them to leave and take it all with them. Among his belongings is a pamphlet about a talk on black holes and the uncertainty principle. As they go, Eugene tries to assure his mother that Torchwood will make things right, but she can't hear him.
Eugene follows the team back to headquarters and admires their equipment. Owen figures that Gwen feels guilty about Eugene's death since he had a thing for her. She does Eugene's autopsy and he watches on in horror before fainting dead away. Ianto locates the driver of the car that hit Eugene, and who claims he hit Eugene and drove on, thinking he'd be okay.
Eugene returns to his home and watches as his mother cries in sorrow.
After the autopsy, Gwen thinks something is odd about Eugene's suicide but Owen and Tosh dismiss her concerns. Later, Gwen discovers Owen watching Eugene's DVDs and takes them back to the store. On her way there, Gwen goes to the café where Eugene used to eat lunch and goes through his cell phone photos of people's feet. Eugene follows her and suggests she call his friend Gary, and he does. Gwen leaves a message on Gary's phone that she'll call later and then goes to the DVD store to return Eugene's DVD. The clerk, Josh, dismisses his friend Eugene as a loser and wonders if he committed suicide.
Next, Gwen goes to the telemarketing firm where Eugene worked. She locates Gary from the photo of his feet and he's clearly one of the few people upset at Eugene's death. Another woman, Linda, is also upset and tells Gwen that Gary wasn't that good a salesman. Linda claims she has something to say about Craig, Eugene's boss, and Gwen agrees to meet her for lunch later. As Gwen goes through Eugene's desk, she finds another pamphlet on the black holes lecture. She gets a call from Owen asking where she is, and Gwen says she's on an errand.
At lunch, Linda explains to Gwen that Eugene said he was planning on selling an alien artifact to buy a ticket for her to Australia. As they talk, Gwen gets another call from Torchwood but ignores it. Linda talks about how Eugene showed Linda and the others the eye and says he was going to sell it on eBay. The bids soon began to roll in, but Linda never learned who bought it and Eugene can't remember. Eugene's mom Bronwen calls Gwen to tell her she has something Gwen should see. At the Jones home, Bronwen shows Gwen the recording of Eugene at the maths competition. Bronwen explains that Mr Garrett gave Eugene the eye as a consolation prize and denies that her husband left because of Eugene. She claims he went to America to work for a major corporation but Terry says that Eugene used the Internet to find their father's location in Cardiff two weeks ago.
As Gwen goes to see Shaun, Eugene remembers that he went to see his father and realized everything was a lie. As Gwen goes to see Shaun, Eugene asks her to stop and she seems to hear him. When he says he's sorry, she says "It's okay." and drives away, despite the fact she seems unaware of Eugene's presence.
Back at the Hub, Jack asks why Gwen turned her phone off. She tries to explain why she's obsessed with the case and with some prodding from Eugene, she tells Jack about how Eugene sold the eye on-line. Jack suggests it might be a Dogan Sixth Eye and there's a market in them. He agrees to let Gwen check it out for a few more days.
Gwen goes to the black hole lecture at a museum and spots Gary. He finally admits that he set up fake alias to bid on Eugene's eye and boost his spirits. However, then someone else started bidding. Eugene talked to Gary and said he thought the alien had come to get is eye and was using eBay to purchase it. Gary remembers that Eugene had an appointment with the buyer at a restaurant. When Gwen asks him about the photos of shoes on Eugene's camera, Gary thinks they're just random and admits he misses his friend.
Gwen goes to her hotel room and looks at the photos of shoes, while Eugene tries to remember more of what happened. He remembers going to a shiny building with the word "Happiness," but then realizes he doesn't want Gwen to learn what happen. Once she does it'll end. He admits that he loves her and Gwen seems to walk toward him as she stands by the window. She pauses for a moment and then closes the drape. As she sleeps that night, Eugene sleeps next to her in the bed.
The next morning, Gwen gets a call and locates the building that Eugene went to: a Happy Cook restaurant. As Gwen goes inside, Eugene remembers meeting Gary and Josh, who told him that they bought the eye as a joke. There was actually one legitimate final bid but they went 50 pounds over. When Eugene learns they can't pay, he takes out his cell phone and inadvertently takes photos of their shoes. Furious, Eugene insists the alien is out there somewhere but Josh says the other bidder was a Mr Blackstaff, a collector of alien ephemera and Nazi memorabilia. He figures he can get some money for the eye from Blackstaff.
Gwen talks to the waitress, who remembers the fight. Rather than let Josh have the eye, Eugene swallowed the eye. Gary and Josh tried to get him to throw it up but Eugene ran out. As they talk, Eugene and Josh come in and Josh asks the waitress not to talk to any women who come in. Gary points out that Gwen is there, and Josh tries to run for it. Gary trips him and admits that he misses Eugene.
Gary and Josh explain that Eugene ran out across the road and they lost him. Eugene remembers that he ran away, stopped on the road, and was run over. He realizes that the eye gave him the chance to look back on his life and realize what it really was.
Eugene goes to his funeral and watches as Gwen and Gary go there. His father Shaun is there and Bronwen gets up to speak about her son. When she can't bring herself to talk, Shaun speaks of his son and how things went wrong and he couldn't be there for Eugene. Eugene realizes that his father was just an ordinary bloke who messed things up.
Gwen goes to the cemetery and has the mortician recover the eye. Eugene wonders why he's still there. As Gwen walks down the street from the church, she talks to Eugene as if he's there. The Torchwood team arrive and she shows them the eye. Gwen asks for five minutes and starts to approach the Jones family outside the church. A SUV drives down the road, approaching the oblivious Gwen. Eugene dives at her and pushes her out of the way. Gwen looks up and sees Eugene, and Eugene realizes everyone can see him. Gwen kisses him in thanks and Eugene gives her the eye back. He disappears in a flash of light and rises up and away from the world.