I wanted to like this week’s Doctor Who much more than I did. It’s not a terrible episode ([insert random snark about “Let’s Kill Hitler” here]), but after Twelve’s rock-idol return in “The Magician’s Apprentice” and the beautiful character scenes of “The Witch’s Familiar,” any story would have to be really special to even hope to measure up. And this one wasn’t quite there.

But even if the great moments of “Under the Lake” didn’t add up to a great episode, they were still great moments.

Especially one.

As written by Toby Whithouse and directed by Daniel O’Hara, “Under the Lake” is your traditional Base Under Siege story, in which The Doctor and his companion[s] of the time – here, of course, it’s Twelve and Clara – stumble upon a small base where the crew is under attack by mysterious forces nobody can fathom.

In this case, “fathom” is very much the right word, as the base in question is underwater. And the mysterious forces in question might or might not be ghosts (though, given that Doctor Who is typically all about Clarke’s Law, it’s no spoiler to guess that they’re really aliens taking the ghostly forms of their victims). There’s much running, of course, and a few designated redshirt deaths (including the obligatory Corporate Weasel), as we’ve seen so often enough.

But where that sense of familiarity worked so well in “Last Christmas,” it works against this story. Because we have been here before – in other bases, with other Doctors, running from other monsters – we never quite feel the sense of dread we should be feeling. And while that cliffhanger is another huge, NOOOOOOOOOOO!-worthy shock, it doesn’t hold up when you remember that there are still quite a few episodes left in the season.

But for all its issues, it’s still an entertaining episode. If the plot’s not quite what it should be, there are plenty of neat little bits of character to carry us through. One is a wonderful scene where Clara tries to coach Twelve in the art of talking to frightened humans – seriously, she has flash cards and everything. Another is a tense sequence when they’re separated near the end of the episode. It’s a measure of how much their relationship has grown since “Deep Breath” that when Twelve promises he’ll come back for Clara, she trusts him without hesitation.

But the best thing about “Under the Lake” is something so big that you might not even realize how big it is.

After the base’s captain is killed in the opening, command falls to a woman named Cass. Cass is deaf. And except for one scene where she uncovers a vital clue by reading lips, that fact is entirely irrelevant.

Cass is a well-written character, very well played by Sophie Stone. Nobody questions her authority, not even Twelve (who shows a genuine respect for her). Her deafness is treated as a mere fact of her life, not the defining element. And there’s a quiet tenderness to her relationship with her interpreter Lunn (Zaqi Ismail, also excellent) that lets you care about them in a way you don’t get to do with the rest of the crew.

Nothing in that last paragraph should be noteworthy. But how often do we see a character with special needs treated as just another person? More than that – how often do we see that character treated as someone to be respected, trusted, listened to, followed? How often is that character allowed to be fully human?

Not often enough. So to have an actor like Sophie Stone (the first hearing-impaired performer cast in a major role on the series), playing a character like Cass, in a show like Doctor Who, and to have it all treated so casually, is nothing casual. It’s representation. It’s inclusion. It MATTERS.

Whatever flaws I saw in this episode, in that one moment, when it really counts, “Under the Lake” is a success.

Thanks as always for following along. I’ll have another review for you next week, once we’ve all seen “Before the Flood” and learned how they’re going to get out of this one.

Until then…