Sergeant Callum Stone is on duty ,but is he up to the job when a call comes in about a young woman, Zoe Williams, who has been found badly injured under an open window? Callum’s just heard his dad is dead but keeps the news to himself and makes some unpredictable moves…

Pcs Kirsty Knight and Nate Roberts are first on the scene and get Zoe rushed to hospital while they try to work out how she fell. Callum shows up late and in a foul mood, then Denise Jones (Sharon D Clarke – Lola Griffin in Holby City) arrives and tells the officers Zoe shared the house with her and Selina Morris. What Denise fails to admit but what the officers discover is that she’s running a brothel and that Zoe and Selina are prostitutes. When they talk to Selina, they find out their pimp, a loathsome creature called Dylan, had found out that Zoe was withholding earnings so she could save up and run away. It seems Dylan got to Zoe before she could run, though, and pushed her. But the officers can’t prove that.

Frustrated, Callum has a word with Zoe’s father Martin, who beats the pimp to a pulp. Has Callum crossed the blue line? Kirsty thinks so and confronts him.