Episode 8

In the weeks after Fiona's death, Adam is handed a case that smells of trouble before the paperwork lands. Oleg Korsakov is a Russian multimillionaire whom the government has taken to calling the saviour of the NHS. His money is enormous and his timing is perfect. Every instinct Adam has says the rescue is too good to be true. Ben Daniels plays Korsakov with the kind of smoothness that makes you check your pockets afterwards.

The second thread is older and colder. An old British traitor is pulled back in to infiltrate a Russian firm suspected of stealing secrets straight out of GCHQ. The two investigations run side by side, and the episode is in no hurry to explain how they join. It lets the audience watch the join happen, which is more satisfying anyway. The Russia of the hour is the post-Soviet kind, where fortunes were made overnight and every fortune has a story it would rather not tell.

The paranoia is the draw. A billionaire arrives with a cheque big enough to save a public service, and the state's first question is what he wants in return. There is a terrible plausibility to it. Money this big does not come with questions attached; it comes with answers already prepared. Nobody at Thames House quite believes in the miracle, and the episode is better for their suspicion.

Howard Brenton and David Wolstencroft wrote it, Omar Madha directed. Peter Firth's Harry oversees the mess with Anna Chancellor's Juliet, Raza Jaffrey's Zaf and Hugh Simon's Malcolm Wynn-Jones, while Janet Amsden's Madeline, George Baker's Hugo Ross, Phyllis Logan's Diana Jewell, James Dicker's Wesley Carter, David Burke as Fiona's Father and David Fleeshman's Malcolm Stackley fill out the edges.

But the sharpest scenes belong to Daniels, whose Korsakov wears charm like body armour. Saving the NHS is a cause nobody can argue with, which is exactly why it makes such a comfortable disguise. The episode knows it, and it lets you in on the joke.