Harman and Hemmingway arrest a young girl following an incident of criminal damage, but during the interview, she claims that she was raped the night before. Thatcher and Drummond are assigned to the case, and they investigate a man seen following the victim on CCTV footage. However, when the man is given a rock solid alibi, Thatcher starts to doubt if the woman was raped at all. Meanwhile, Hollis investigates an altercation between a schoolboy and his teacher, but the young boy refuses to speak out against his real attackers. When he and Chambers go train-spotting after their shift, they watch on as the young boy is set upon by a gang, only to discover that the victim may be the ringleader.