Melanie strives to track down Layton before he can reveal her secret, and will stop at nothing to do so. Layton, for his part, is still trying to start a revolution. In First Class, machinations against the head steward continue.

One of the most refreshing things about Snowpiercer as it goes on is the way in which characters which could be cartoonish versions of good and evil very easily are instead made into complex, breathing people with all of the attendant complications in their actions and relationships.

The lion’s share of that goes to Jennifer Connolly’s Melanie Cavill, the de facto commander of the train who must enforce its terrible, unfeeling regime. Here, we see her using every awful resource and capability at her disposal as she desperately tries to track down Layton before he can release her secret to the rest of the train. She isn’t above blackmail or threats – emotional and physical – but what’s interesting here is not what she does, but its impact on her.

There must obviously be some impact on someone who has to lie to most of their colleagues and closest associates as well as an entire train full of people. What’s perhaps less immediately apparent is the psychological stress on her in having to do the necessary things to maintain the order of Snowpiercer. Here we get a glimpse of that, and of a fragility beneath the steely surface which speaks not only to the sort of person Melanie Cavill really is but also how good an actor she must be.

Whether she’s manipulating someone’s deepest fears, pulling levers with people she knows are important to her enemies or simply carrying out an interrogation herself, what’s clear as the episode progresses is that Melanie’s waters run deep indeed.

And while she’s distracted with her quest to protect her secrets, others are moving against her. Ruth, enjoying a day off is taken by surprise by an unexpected dinner invitation. But as with most things in the upper echelons of The Train, all is not quite what it might appear. The question is, can Ruth’s loyalties be swayed, and if so, by what or whom?

As for Layton, he’s a man on a mission, doubly so when Melanie overplays one particular hand. Now she’s probably made him as dangerous as it’s possible for him to be, and worse, she probably realises it. As he prepares to weaponise his sole remaining trump card, it’s difficult to see how mass violence won’t be the result in the very near future.

Verdict: A fascinating character piece which is managing to wring an awful lot more out of its central premise than I’d initially anticipated. 9/10

Greg D. Smith