Marvel’s Agent Carter” was a hit with critics right out of the gate (if not a ratings juggernaut, more’s the pity), but in the show’s zippy second season, the ABC drama has undeniably found its groove; evolving into a confident and consistently compelling confection that effortlessly manages to blend energetic spy hijinks and adroit humor with disarmingly incisive commentary on the gender politics and racism of 1940s America in general and Hollywood in particular — an examination that is still relevant today.

Marvel and ABC made episode 204, “Smoke and Mirrors,” available to critics, and after watching, Variety caught up with star James D’Arcy — who plays Peggy Carter’s (Hayley Atwell) unlikely partner in crime-fighting, Edwin Jarvis — to discuss the broad strokes of Season 2 and the joys of working with Atwell.

To me, this week’s episode manages to be both the funniest of the series so far and also the most poignant, offering us a glimpse back to Peggy’s past. Did you get a sense of that when you read the script (written by Sue Chung)?

I agree with you – I really did, and I have two further things to add to that. One is, with all seasons, it takes an episode or two to set up what your story is. It’s inevitable that there’s going to be exposition, as there is in every show — we’ve got to tell you what’s going on, and then at some point you settle in to what the show is. And I feel that what you see in episode 4 is only the very beginning of what the next six episodes offer. I think that it becomes funnier and more poignant as the show goes along. And the show now treads that line really beautifully for the rest of the season. And obviously [also] lots of action and all the other stuff that you hope will come along with a show like this.

Jarvis certainly has some of the most comedic moments of the series, especially in this week’s episode – how often do you and Hayley break?

We’re pretty bad, I’ll be honest, we’re not good. They’re used to us now, but in Season 1 with this American crew, looking at these two British actors who… we get the work done but we laugh a lot. I don’t know that they were quite ready for that. There were definitely some raised eyebrows for a while. Now they just kindly tolerate us. [Laughs.] Sometimes we make them laugh as well… but we’re not doing it for those reasons. We insist on having a good time on the set. I think that stuff shows on screen in the end. You pick up on it somewhere subconsciously, and we have a real interest in that, because that’s our lives… the show is 10 episodes long – that’s four months of our lives, so I’m gonna have a great four months, and Hayley’s just the best foil.

How much are you able to improvise? [D’Arcy mentioned a specific line in “Smoke and Mirrors” that was improvised, but we’ve redacted what it is to preserve your enjoyment of the scene.]

We shoot the script, and the writers are completely brilliant – they’re all Americans and they write English period dialogue better than most English writers, but if I think of a [great line] and we get three takes, I’m gonna try it. I’m gonna give it a go. And some of them land and some of them don’t. I better not say what it is because it was cut, but there was a moment in Season 1 I was so proud of the improvisation I came up with and they didn’t use it, so I’m thrilled that to discover that my next favorite improvisation has made it into the show.

It was fascinating to explore some of Peggy’s backstory in this episode – Hayley is such a nuanced performer, and you’ve obviously had the chance to see her inhabit this character up close for two seasons now – what’s the most satisfying part of working with her?

I wouldn’t even know where to start, I love that girl so much. She’s just the best. She’s a fantastically skilled, nuanced actress. She’s really funny, she’s really kind. I just gel with her – we’ve known each other for 10 years, we were friends before the show, but we’ve spent so much time together that we’ve become very close friends. I admire her. I’ve played leading roles on television before, I know the kind of pressure that you get when you’re in that position and she is very, very graceful about all of that. She works her little tush off, she shows up, she knows all her lines, she’s great at the action sequences, she’s on set first thing in the morning and last thing at night the way that nobody else on the show is, and she does it all with a smile on her face, and then she’s brilliant on the show… There’s some parts of every character that you get for free – this is who that person is, and Hayley is just a very, very decent person with a strong sense of what’s right and wrong, and yet doesn’t shove it anyone’s face. I don’t have enough superlatives for her.

Since we’re delving into Peggy’s backstory, are we going to get a chance to explore Jarvis’ at all this season?

We do take a little step back at one point, but it’s not quite in the way that we explore Hayley’s childhood. We take a little step back and the way they’ve written it is very satisfying to people who’ve been watching this show since we began. And more than that, I better not say because it will slightly spoil it, but what we also do is… [explore] this relationship that, in my experience the fans were excited to see, Jarvis’ wife … now we’ve actually met her, she’s a really crucial part to what happens this season.

Marvel’s Agent Carter” airs Tuesdays at 9 p.m. on ABC.