The next problem is actually a bigger one: As I and many others have pointed out, Clara just isn’t a very well-developed character. She has traits—smart, resourceful, a dab hand with witty repartee—and Coleman plays those traits adroitly, but what is her motivation for traveling with the Doctor, or really, doing anything?

The main thing even Moffat can get a handle on to define Clara’s relationship with the Eleventh Doctor is good-ol’ UST: Unresolved Sexual Tension, the will-they-or-won’t-they dynamic that has fueled many a sitcom. They “fancied each other,” in British parlance, and now she’s bummed that he looks old. The Doctor, for his part, seems to feel a bit sheepish about having being attracted to her at all, because he actually always was old, centuries old, even when he looked like Matt Smith.

That’s a pretty thin emotional reed on which to hang an episode, but it does at least have the virtue of ringing true.

“He flirted with you,” Vastra explains.

“How?” Clara replies.

“He looked young! Who do you think that was for?”

“Me?”

“Everyone.”

The idea of the Doctor “flirting” with the universe, hoping to be accepted by means of looking like someone’s “dashing young gentleman friend,” is a poignant one. Yes, it’s ageist, but the Doctor does spend an awful lot of time on Earth, where, even in the 21st Century, ageism is, in fact, a thing. It also brings to mind a similar post-regeneration episode: “The Christmas Invasion,” David Tennant’s first full turn as the Tenth Doctor after he’d regenerated from Christopher Eccleston’s Ninth. Aside from spending a good chunk of their respective debuts in borrowed bedclothes, both Ten and Twelve go through a very rough regeneration that involves a lot of sleeping, some erratic behavior, and two seriously freaked-out incumbent companions.

In a way, those two regenerations mirror each other. The Ninth Doctor fell in love with Rose Tyler, but he appeared much older than the 19-year-old Rose. So he got younger—and the Tenth Doctor and Rose became more obviously a couple. Perhaps the Doctor missed that feeling, which would at least partially explain his infatuation with Clara. And then, with several hundred years to sit around and think about it (wow, yep, still hate pretty much everything about that Trenzalore storyline...), he realized (again) that he just can’t have that kind of a relationship with a human being. So he got older, providing Clara with an implicit statement he later made explicit.

“I’m not your boyfriend,” he says near the end of the episode.

“I never thought you were,” she replies.

“I never said it was your mistake.”

Despite the slower pace, “Deep Breath” still throws a lot of stuff at the viewer, much of it top-notch. The Doctor and Clara realizing that they’re the only living people in the restaurant delivers a powerful jolt of Lovecraftian body-horror. Clara’s effort to escape the droids by holding her breath is deliciously tense. The Doctor riffing on his “attack eyebrows” works for a chuckle. The Scottish jokes stop just short of being too much. And Vastra and Jenny finally share a kiss. Well, sort of.