I can’t remember the last time I had feelings this mixed about a season of Doctor Who, new or old.

On the one hand, I can’t deny that the quality of the show is at a local maximum. Acting, cinematography, writing, conceptual sophistication, special effects, direction — it’s all at least as good as it’s ever been. When the weakest episode of the season is still as entertaining as “Robot of Sherwood” or “Time Heist” (take your pick), you’re doing something right. There are already three episodes this season I’d be willing to back as my favorite of the year, and it’s not over yet.

On the other, I find that I’m seeing all this from an emotional distance. Even though I know the stories have been good, I find that I’m not as eager to watch them as I used to be (I don’t even mind that iTunes won’t give me the new episode until after midnight Sunday morning, and it’s nothing to wait a day or so before watching it), and I’m less willing to care about them. There’s something healthy about this — moderating my excitement means minimizing potential disappointment — but it seems like a step in the wrong direction, and I’m not the only person I know who’s taken it.

Is it just that both the Doctor and Clara are spikier this season, more flawed and interesting but more prone to bickering and lying and being unpleasant to each other and the people around them? There’s a recurring idea that both of them are addicted to danger and the excitement of travel, but there have been precious few journeys they’ve taken this year that truly seem wondrous and beautiful. Even that gorgeous train last week turned out to be a fake.

Be that as it may, I loved “Flatline.” It’s one of the three favorites I mentioned, along with “Listen” and “The Caretaker.” When I heard that one of the plotlines this season would include the TARDIS shrinking, I thought: what a dreadfully dull idea. Well, not only was I forgetting that it had been done before in Doctor Who in quite an exciting episode (1981’s “Logopolis”), but I should have realized there’d be a lot more to the story. Likewise, I was worried because I understood this would mean a Clara-heavy episode, and I’m still not her biggest fan, but the back-and-forth between her and the Doctor worked out extremely well. It’s an episode that combines all the elements I love in Doctor Who: comedy, memorable visuals, intriguing ideas, and genuine peril.

Capaldi and Coleman play the comedy flawlessly, from the sight gags inherent in having a TARDIS from which the Doctor can only extrude his hand (or, in one of my favorite bits, a sledgehammer) to the business of Clara pretending to be the Doctor in his absence, complete with “companion” in the appealing graffiti artist Rigsy. This episode proves, as did “The Caretaker” and “Mummy on the Orient Express,” that we can have solid character moments without rendering the whole affair angsty and ponderous. As a classic series fan, I have difficulty judging the success of visual effects which for me are always going to be better than bubble wrap painted green, but I thought both the “flat” and “3D” renderings of the creatures and their victims looked beautiful and fantastic, perhaps apart from the “Photoshop blur” moments, as my girlfriend called them. The scenes of people being snatched into 2D were legitimately frightening, played for real, and the optical illusions of the various doors and the fate of the penultimate victim looked as good on my TV as on my iPad.

Ideawise, I’d guess Mathieson extrapolated from optical illusion graffiti (and perhaps the book Flatland) to the idea of creatures that live in two dimensions dragging us into their world, either from curiosity or something more sinister. Like most Doctor Who ideas (and probably 90% of TV science fiction, if we’re honest), it doesn’t quite stand up to close examination, but as an idea to drive a science-fantasy plot for 45 minutes, it’s terrific. Mathieson gets a lot of mileage out of it, not just using the flattening as a frightening way to die, but also using it to turn doors into pictures of doors and trap people, and to remove potentially fatal obstacles (like trains) by flattening them. I think the only really terrible idea here was the Doctor’s name for the creatures: “the Boneless?” Like “the Foretold” last story, it feels just a little too much like a self-conscious New Doctor Who Monster name, even though it’s lampshaded by having the Doctor himself name them. Why not “the Flatteners”? Too Stephen King?

As for the genuine peril: as the Doctor notes grimly at the end, people died. Not even the “right” people. In real life, I wouldn’t be happy about this, but in a Doctor Who story, it just feels more honest, more real. There’s something at stake here, when with a lot of the “everybody lives!” endings we’ve had ever since Moffat’s first New Who story, there hasn’t been once we’ve learned the trick. Most importantly, though we can’t be sure, it does look as though the monsters are genuine monsters, their intentions either hostile or so alien that they might as well be. Again, not something to celebrate in real life, but so refreshingly unusual of late that it seems champagne is in order.

No mixed feelings about this episode. More like this, please.