Nadir and Hunter investigate when a number of witnesses make complaints against a market trader, claiming that the perfume that he sold them has left them with scarring and burns. When the pair discover that Chez Williams, one of Nadir's former informants, has been running cases of the perfume to local pubs and clubs, they attempt to use him to crack the case. Meanwhile, Turner and Nixon investigate a suspicious death when a couple claim to have found an unidentified body in their living room. Hardy and Keane investigate when they suspect that a young man is faking his mother's dementia in order to steal her personal possessions, but Hardy isn't convinced of the man's guilt.