In the second episode of the last series, Shearsmith and Pemberton strip it back once again in this two-hander thriller, that taps into a philosophical dimension of human decision-making and misdeeds. 

On a rain-strewn night at his remote country home, therapist Blake Chambers (Pemberton) brings home a stranger (Shearsmith) who seemed to be contemplating jumping from a bridge, but was it wise?

As you would expect with these two, the acting is of incredible calibre here and arguably powers on what seems quite a simple premise of beware the outsider, though – naturally – things soon twist, as do your perceptions. “The Trolley Problem” is a psychologically fuelled dark thriller, that feels rather theatric at points, dotted with a number of laughs (Mary Berry!) but this one plays things a bit (okay, a lot) more serious this week. Which is saying something considering where last week’s incredible series starter finished off.

Arguably this one is somewhat overshadowed by other episodes of its ilk across other seasons, like the sublime “The Riddle Of The Sphinx”, in that it is a singular setting story that relies on a limited character roster and a clever narrative built on changing allegiances, twists, early clues, and personal tragedy and human storytelling. 

Still, this one plays out in a very compelling fashion and the shatteringly memorable conclusion and final frame is among some of the more apt, twisted and jet black endings in the show. Ensuring that “The Trolley Problem” does leave an impact overall. Even if some of the bleak edges of this one might have some of you crying out for a Wilma Dickshow wisecrack!

Series nine continues its groove with an atmospheric second episode, and the writing remains ever impressive, just as the characters continue to leap from your television screen. Bring on next week.