Jack (John Barrowman), Owen (Burn Gorman), and Gwen (Eve Myles) are chasing a man through the streets of Cardiff while Toshiko (Naoko Mori) tracks an alien energy that accompanies him. Gwen manages to chase him down into a train station and grabs his jacket as he gets away. There is an alien device in his jacket pocket and through it she sees a brief emotional vision of the past—a lost boy wandering in a train station.
The boy has a name tag, and they track it down to an old man, Tom Flanagan (John Normington), who says he was sent to Cardiff during the World War evacuations and was terrified. They determine that the nanotechnology of the ghost device—actually a quantum transducer—lets one see moments of strong emotion in the past.
The suspect, they learn, is Sean Harris, called Bernie (Ben McKay), a petty thief from the town of Splott, and they go there looking for him. They find nothing and return to the train station, where Owen activates the device under a bridge and sees the rape and murder of a young woman, Lizzie Lewis (Emily Evans) in the Sixties by a man named Ed Morgan (Christopher Elson when young and Gareth Thomas when old). Owen wants to bring him to justice though the case is long closed, and he begins to track the man on his own. He confronts the man but gets no information out of him but leaving his house he spots Bernie and gives chase. He catches him and takes him to a pub to learn about the device. Bernie says he found it in a tin of random objects, and he saw the murder too. Torchwood follows Bernie back home to retrieve the other half of the object. He only used it once himself, says Bernie, and he saw himself bleeding to death in the future. When Gwen touches the object, she sees herself holding a bloody knife and calling for Owen. Jack tries to calm her down.
Ed Morgan is paranoid and depressed, and Bernie is blackmailing him. Ed has left home and is on the way to Bernie’s with a knife. Torchwood arrives just in time to disarm Ed. Owen takes the knife away from him and decides to avenge the girl. Gwen takes the knife away from him, but Ed impales himself on it. They fail to revive him. The device goes into the sealed archives.
Jack gave chase in a car because John Barrowman sprained his ankle. Burn Gorman was sometimes not on set because his wife gave birth to his son while the episode was being filmed. The general feeling is that Owen was so keen to avenge the girl because he had just finished date-raping a man and woman using alien pheromones and felt a bit guilty about it. Gwen is extremely upset about the knife because she doesn’t even kill spiders in the bath.