The sound of massive bulkhead doors closing echoes around them in the dark as all the doors slam shut and seal in an unplanned lockdown. Then there's a sudden ominous whoooosh sound and in the space of mere seconds, the air starts losing heat, chilling down to below freezing.

There is also a pungent smell that fills the hall as the cold causes an important gas piping system to go brittle and snap, and run-off gas from the oxygen recyclers -- mostly carbon dioxide -- starts to fill the twisting hallway. Before long, they'll all start to feel their lungs struggling for air, the sensation even worse because of the biting cold.

Most of the bulkhead doors are massive and unbearably strong, meant to resist incredible forces breaking through them -- something that even a metallokinetic and a plasma-spitting dragon might find impossible to bust through. But there is one that didn't seal properly, that's visibly thinner and clearly meant to be a simple door rather than an important seal for the section. That one can potentially be broken to allow them to escape the rapidly worsening conditions.

If they can find it in the dark.

Between the cold and the carbon dioxide, there are only minutes on the clock. Tick-tock.