The Vice - Series 4

When prostitutes are murdered in the financial heart of London, Chappel reaches out to working girl Sandra, warning her to stay away from the unit's prime suspect, arrogant financier Gordon Ellis. Chappel uncovers a link between the murder victims and Ellis, but Hutchins isn't so sure that CCTV footage supposedly capturing the second victim with Ellis is concrete. As Chappel grows dangerously involved with Sandra, he becomes obsessed with nailing Ellis, and sends PC Kirsty Morgan undercover in an attempt to prove his involvement. Meanwhile, a sceptical Robinson receives news of his promotion, and announces he is leaving.

Chappel is delighted when retired prostitute Clara comes forward and offers to give evidence against Keith Beaumont, a former porn baron whom Chappel suspects is still operating. However, past encounters with Beaumont begin clouding his judgement and enthused by her boss' take on the task, Morgan offers herself as bait in a dangerous undercover honeytrap. Suspecting that Morgan may well have slept with Beaumont, Robinson persuades his new boss to allow him a week's secondment back to Vice to give Chappel a hand in his quest to prove Beaumont's guilt.

Chappel goes undercover as an insurance-broking lodger to investigate a suspected porn merchant, who makes a sideline in dirty movies whilst running his own above-board video rental shop. However, when he learns that the residence is in fact the base for a paedophile ring, the case is recategorised and taken from Vice, leaving Chappel furious upon discovering that the case has been handed to Robinson – his first assignment since his promotion to Inspector. Meanwhile, as Hutchins begins questioning her loyalty to Chappel, the latter—unable to continue allowing the repeated abuse of a 12-year-old girl—attacks the prime suspect, eliminating any chance of bringing down the ring.