DI Chappel has been transferred to a desk job and DS Vickers has been drafted into the Vice Squad. PC Hutchins goes missing during an undercover operation into a pornographer, and Chappel risks everything to save her.

Inspector Joe Robinson returns to the Vice Squad, and attempts to nail a violent pimp. The mother of a young prostitute threatens to reveal details of her lurid past with DS Vickers.

The Vice Squad investigates an amusement arcade manager suspected of recruiting young runaways as rent boys. PC Sparkes is in a tricky situation as the male teenager who has been befriended by the amusement arcade manager, takes a shine to him and makes his undercover role uncomfortable. When the Vice Squad perform a bust he is mistaken for a punter.

The manageress of a pole-dancing club suspects her uncle of using it to run a prostitution racket. DI Robinson sends DS Vickers under cover to investigate but is conerned that his boss may be colluding with the suspect.

The Vice Squad assists the Serious Crime Squad to investigate the murder of a prostitute, with PC Morgan acting as liaison to the senior investigating officer.

DI Robinson investigates a club owner suspected of encouraging drug dealing on the premises, only to find that the club is a base for human trafficking.

PC Johnstone's relationship with a known pimp is discovered. DS Vickers attempts to use her for his own ends.