This week’s episode—Oxygen—is the first to show Bill in serious danger, courtesy of a malfunctioning spacesuit that nearly kills her and also, ultimately, saves her from dying: a dichotomy that seems to point to the uneasy relationship some people have with capitalism—a theme that is explored here. And again racism is challenged. I’m reminded of classic Star Trek episodes that score an A-plus for science fiction, while still finding time to scrutinize modern-day prejudices.

Not surprising, then, that the Doctor’s first line is “space, the final frontier.” Although, Oxygen—which too easily slips into on-the-nose dialogue in an otherwise solid Doctor Who episode that expertly knits chunks of knotty science into the plot—probably deserves a B-minus at best.