On a night out with her friend Lynn, Cass Rickman meets two men, Jamie and Ben, who offer her some dope which she refuses. To her horror, Ben is arrested the next day by DS Boulton for possession of drugs, a charge which Ben manages to drop onto Rickman when he insists the drugs are hers. Rickman is investigated by CIB, and things look bad for her when her friend Lynn makes a statement that Cass took drugs the previous night. DS Beech and DS Boulton follow Lynn and discover that she is the drug dealer, and she is linked to another dealer, Cairns, whom Boulton has been after for a long time.