Jack, Owen, and Gwen, pursue Bernie Harris, a petty thief carrying something emitting an alien signal in his jacket, through the Cardiff streets.
Gwen discovers an alien device in the jacket pocket, and when she activates it, she sees a vision of a lost boy called Tom Flanagan wandering the train station in 1941.
The Hub's computer analyses that the nanotechnology of the "quantum transducer" allows people to see moments of the past spurred by strong human emotions.
Bernie explains he found the device in a tin of random objects from an old lady, and that he too saw the murder of Lizzie, and wonders if the team wants the "other half".
As they leave, Gwen accidentally triggers the second half, and has a vision of herself holding a bloody knife, calling out to Owen.