Under Wraps

"Under Wraps" is the eighth series' most efficient thriller — a poisoning, a blackmail and a ransom in gold and diamonds, all built around the series' oldest trick: the respectable man with a secret past. The victim is Hungerford, taking a two-week break at the Cedars, a nursing home run by Sir Matthew Osterson — a man who, the episode slowly reveals, did secret work in nerve agents and ran the tribunals that assessed compensation claims for the men damaged by them. One of those men, H. Wilberson, contracted a wasting disease, had his claim dismissed, and has now returned to the island in a wheelchair, with a vial of poison and a plan.

The blackmail note, found after a vet dies drinking from a poisoned water trough, threatens the patients unless a million pounds is paid in gold and diamonds. Bergerac, Willy and Ben are told to work it in secret. The plot is handled with the series' usual care — the lab assistant who stole the vial, the girlfriend who taught the children whose creative-writing assignment was doctored into a ransom note, the motorcycle courier who snatches the payment. John Stride plays Osterson with a worn, conflicted dignity, a man who built weapons and now runs a home for the elderly, and the episode never lets him off the hook: the poison was his invention, and the man in the wheelchair was his victim.

The resolution turns on Whittaker — the wheelchair-bound patient who is Wilberson, selling his house six months ago to fund his revenge. The vial, the keys, the plan of the Cedars, all of it is his work. The ending is properly grim: the poison, the deaths and the ruined lives resolve into a portrait of a man who was failed by the system and decided to become its punishment.

It is a contained, well-made hour that shows the eighth series could still do a tight thriller with a moral spine. The nursing home gives it a closed setting and a sense of vulnerability, and the question of who is guarding the guards runs underneath. Bergerac, as ever, is the man who sees the pattern behind the respectable surface — a nerve agent, a dismissed claim and a wheelchair that was never quite what it seemed. A solid, dark entry that proves the series had not lost its edge.