Missing presumed dead
Lisa Lancaster joins the HVF after the rising.
One day when looking for supplies in a supermarket she gets attacked by Kieren Walker and Amy Dyer in their untreated state. She then disappears from the supermarket. Nobody knows who moved her body and in what state she is.
Throughout the first series Lisa appears again and again in Kieren's mind as symbol for his guilt. She is also a point of guilt for Jem, as Jem was there at the time, but could not decide between not shooting her brother and letting her girlfriend die, or saving her girlfriend and killing Kieren in the process.
Lisa's parents think she will come back to them as a PDS Sufferer when Kieren tells them he attacked her. Even so, Kieren doesn't fully tell them that they are wrong, letting them keep hope - Jem says that he has done the right thing.