Witness for the Prosecution episode one review: Agatha Christie drama starring Kim Cattrall, Andrea Riseborough and Toby Jones

But it looks brilliant, the yellow smoke of a gloomy smogged-out London almost licking the screen and getting in our eyes under Julian Jarrold’s expert direction. The fug also gets in the lungs of our lawyer hero, John Mayhew (Toby Jones) who plies his legal trade in the dark and gloomy alleys of the capital - and its police stations. That's where he meets Vole...

The murder itself was depicted with visual restraint. The image of the pool of blood, and the victim’s cat licking the clotted claret off its paws was chilling enough.

But the question is: did Vole do it? The ex-soldier who has been hired by the sexually voracious Emily for an altogether different kind of service, seems banged to rights.

He was spotted leaving his lover’s home at the time of the murder by her (obsessively adoring) maid Janet McIntyre. He also burned his shirt in the grate and…horror of horrors, his common law wife (Andrea Riseborough’s chorus girl Romaine Heilger, below) has become a witness for the prosecution.

The noose, it seems may as well be put round his neck.

But what’s this? The industrious Mayhew has received a mysterious summons, apparently from a former dancing colleague of Romaine’s who has information on her.

She is not who she seems, it appears, and there seem to be further revelations in the sheaf of letters she has placed in his hand. It’s nicely set up for episode two.

Phelps’ skill here is to play up the impact of the First World War in Christie’s story.

Vole and Heilger appear in a flashback to have met in the trenches – he as a bombed out squaddie, she as a refugee who has somehow found herself front the front line. We see him in an early scene getting fired in a humiliating fashion from his job as a waiter in a posh drinking establishment for dropping a tray; and the sense that the war's heroes are being neglected is powerfully felt.

The War has also claimed the Mayhews’ son. The young lad had lied about his age to get to the front and while Jones' Dad returned with screwed up lungs thanks to a poison gas attack, Mayhew junior did not return at all.

There is a desperate pall of gloom in the lives of Mayhew and his wife Alice (Hayley Carmichael) who still tends to her son’s bedroom things. The two of them eating their dinner in silence was deeply affecting. But there is no doubt the war – more of an incidental detail in Christie’s version - is superbly used to provide the thematic bind for this story.

Mayhew’s decision to take on the case of Vole is clearly bound up with his feelings about his son. While he couldn’t save his own child he is going to do his damnedest to save this young man. But is he a man who should be saved? And just what (if anything) is Romaine hiding?

Tune in tomorrow to find out...