Valentine and Hardy investigate a complaint from a young mother after she is confronted by a man whom she claims is selling drugs on the local estates. When the feud escalates and the man ends up getting stabbed with a needle, the young mother is arrested, but provides enough information for Okaro to mount a raid which gives Hardy a chance to sample undercover work. Meanwhile, De Costa offers to help out her social worker friend Saul after one of his former clients is threatened with a gun. She and Perkins investigate and discover that the young boy's sister is the target, and that the gunman, her ex-boyfriend, is trying to find out where she has been hiding.