Part of Doctor Who's original remit, when it began in the 1960s, was to be educational as well as entertaining for its young audience.
But as time has gone by this element slipped out of the show's priorities.
However, given the rising tide of global ignorance and intolerance, what better time for The Doctor and her new friends to return to Montgomery, Alabama, in 1955 to meet Rosa Parks (Vinette Robinson), one of the key figures in America's early civil rights movement?
The TARDIS is bouncing through time and space, trying to get back to modern day Earth, but stops off in Alabama where The Doctor detects some errant artron energy (which is connected with time travel in Whoniverse science).
Investigating this, The Doctor and her companions - particularly Ryan - quickly come face-to-face with the vile and inexcusable racism of the period, and it's in these historical areas that the episode does what Doctor Who should be doing: informing and educating through drama.
It turns out that a time-travelling racist ex-con, Krasko (Josh Bowman), is seeking to nudge history off-track ... as he's been surgically altered to not be able to take direct, violent, action.
And this is where the trouble arises with Rosa because Krasko is a dreadfully one-dimensional antagonist that feels like an unfinished, throwaway idea - as does his final fate - and was in danger of distracting from the serious message at the heart of the episode.
Given his vortex manipulator and other time-themed kit, I first suspected Krasko was another renegade Time Agent, but it turned out he didn't even have that depth to him.
He's little more than a contrived plot device, rather than a three-dimensional villain for The Doctor to overcome.
This wasn't so much of a missed opportunity as a fumbled attempt to craft an episode that combined powerful, real world, history with a "troublesome alien" element.
A better written episode possibly could have done away with this ridiculous antagonist entirely and just focused on ensuring that Rosa Parks fulfilled her historic destiny.
As a pivotal moment in recent human history this was certainly worthy of a visit from The Doctor.
And some stories are so important that metaphor won't suffice.
I was pleased that nothing The Doctor did distracted from the importance of Rosa's actions (for example, The Doctor didn't tell Rosa to stay seated on the bus, that decision was entirely Mrs Parks's).
The weak villain was an enormous shame as the main story, of trying to keep history on track, and the differing effects that task has on The Doctor and her team, really hearkened back to The First Doctor's "You can't rewrite history. Not one line!"
In fact, I'm continuing to get a First Doctor vibe from this iteration of The Doctor, heightened by her very analogue approach to problem solving: researching in books, writing notes etc
And this I love, I just wish the script quality was on a par with the central performances and the character work by The Thirteenth Doctor, Graham (I'm hoping his eating becomes 'a thing' in future episodes), Yas, and Ryan.
Jodie Whittaker is a perfect fit as The Doctor, and I'm getting to know her travelling companions as the weeks go on, but we've yet to find that magical fusion of a powerful, engaging, story with the powerful character beats that the personalities in the TARDIS promise.