Holmes investigates when a woman is attacked in her flat and left for dead in a particularly violent domestic violence case. She initially suspects that the woman's landlord, Jamie Morgan, is responsible for the attack, but when she catches the woman having a row with her boyfriend, she arrests him for criminal damage, unaware that she has inadvertently jeopardised a surveillance operation on a major drugs dealer. As Merseyside area drugs become involved, Holmes manages to locate the factory where the drugs are being produced, but a sting set up to catch the villains in the act takes an unexpected turn when they become involved in a violent shootout, and take a young boy and his mum hostage.