Alexandr Akimov

Alexandr Akimov is the shift supervisor in the control room of Reactor Four, running a late-night safety test he didn't design and doesn't fully control. He trusts the procedures, trusts his superiors, and trusts a reactor he's been told cannot fail. He's diligent, deferential, and utterly unprepared for what the gauges start telling him.

Sam Troughton plays him as an ordinary company man rather than a hero or a fool, which is what makes the unfolding horror so unbearable: you watch competence and obedience collide with a catastrophe neither can address. The show gives him no speeches, just a face slowly working out that the rules he's followed his whole career have lied to him.