The Dark Side is the 1614th episode of The Bill.
PC Ben Hayward breaks down when telling primary school pupils about the death of his sister during an anti-drugs talk. Sgt. Gilmore is not happy, but the teacher thinks Hayward's sensitivity will help the students get the message, and may also help them trust Hayward enough to report a bully. An old friend of his sister's works at the school, and she asks him out, although when he meets her at a gallery opening, Hayward thinks her friends are dealing drugs. PC Klein and Hayward find the bully, who goes by the nickname "Red", and has been using two fierce dogs to steal money and mobile phones from school children. They trace the dogs to the flat of drug-addicted prostitute Stacy Dodds, and a subsequent search of her flat uncovers a large stash of heroin. Stacy insists her pimp forced her to deal drugs and have sex with Red, and instead of having the dogs picked up, Hayward and Klein search the pimp's boat, finding more heroin. The pair argue: Klein wants to set up an obbo to catch the pimp red-handed, Hayward insists on taking the drugs back to the station. Hayward drops one of the bags when he hears that Dodds' elderly neighbours have been attacked by Red and the dogs.
Susan Tordoff guest stars as the Teacher.