[Note: Spoilers below for the Project Blue Book Season 1 finale episode, "The Washington Merry-Go-Round"]

Well, the book just closed on Season 1 of History's Project Blue Book, and boy, did they save the craziest case for the last episode!

All season, the highly rated drama about 1950s-era investigations into UFOs and other phenomena has seen central truth-seeker Dr. J. Allen Hynek (Aidan Gillen) and Captain Michael Quinn (Michael Malarkey) — the Air Force pilot assigned to keep him in line — looking into actual reports that have bounced between debunkable to unthinkable.

However, tonight's season finale, "The Washington Merry-Go-Round,"ventured into Steven Spielberg territory, as what appeared to be a battalion of spaceships swarmed over the National Mall in Washington, D.C. Too much? Tell that to the countless witnesses who experienced the event back in 1952.

Here, Gillen reflects on the show's torn-from-the-dossiers storylines, sings the praises of his frequent screen partner and reveals that he, too, believes the truth is out there. (Sorry, I had to.)

I know all the cases on the show are pulled from actual accounts, but were you surprised at how extreme this one is?

Aidan Gillen: No, I wasn't, because it's one of the ones that I was more aware of, you know, from just generally through the culture. I think it's exciting that we end in a quite sensational manner with a UFO attack on the Capitol in D.C., fighter jets going up to engage them.

As amazing as that is and as improbable as it is, it's also one of the most widely reported and believable, given that it happened in such a prominent location during daylight with so many witnesses. So I think it's quite plum that we're ending that way and for it to actually be almost one of the more believable reports.

It's been really interesting to see how Hynek has evolved over the season. He's tough to get a read on. Even Quinn mentions at the end that he's pretty crafty.

You know, he's played his cards close to the chest. I think in this episode, for the first time they do lay it out, especially with Quinn. "This is what I'm doing essentially to stay within the fold, so we can do our investigations our way, regardless of whether we or the authorities want to hear [what we find], or whether we hand over the information." It's kind of exciting.

And he doesn't do that until he's seen something himself. I guess it's one of the first times you see him really not immediately jumping to a conclusion that he has an explanation for. He believes it. It's like him having empirical evidence for the first time and being excited. We see him excited by it. There's something ecstatic in the way he's watching these lights over the Mall. In a way, it's stuff he's wanted to see since he was a kid, despite his reasoning. It's nice to see him excited about it.

Was there a point in the real Hynek's career where things did change for him?

I think it was more a gradual thing ... a cumulative thing, speaking to credible witnesses over a period of time who were reporting a phenomena that couldn't be explained. But for our purposes, we are saying that this thing, this moment in our drama, is a turning point for him.

It feels also like a big turning point for the show itself. That final scene ramps up the mythology and takes it into a space that is very, very extreme. Was that Arctic discovery from the files, or is that something that's been created for the narrative?

I think it's something that's been created for the narrative. And I know, it's a big ending to go out on.

It's also a dramatic ploy to keep people even more interested than before, but I don't know it means that the show has to suddenly continue on this sensational level. It's an interpretation. I don't think it's going to be a cheap gag, where you come back next year and somebody wakes up from a dream or that kind of stuff. It's just an interpretation of certain information. I don't think that the show can suddenly change into a radically different type of show or the tone could change that much and continue at that level.

Having said that, I don't know where the show is going next. I haven't had discussions with the writers, personally.

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I was hoping the finale would at least give us a little more information as to who the Man in the Hat is.

Yeah.

And then we find out that there is a bunch of them!

[Laughs] You know, when the Man in the Hat — our main Man in the Hat — says a couple of things in the later episodes where he implies Hynek is working for him, or working for them, it's as confusing for Hynek as for anyone else about what he's on about. It certainly seems he's somebody who is in line with possibly an extraterrestrial league rather than just a government stooge.

Again, maybe it's just about wrapping up the excitement and giving bit more intrigue for the audience. I don't have the answer to that question. Hopefully we will get an answer to that question in Season 2. That's Ian Tracy, his character's the last person we see in the season.

And he's the person who has also left Hynek the note saying, "Your services are no longer needed." Correct?

Yes, it's disappointing to hear. Just when things are getting going, "Your services are no longer needed." Return to your civilian life? That's not going to happen. I don't want to be confined to come back to my suburban house and watching the stuff on the TV. [Laughs]

Let's talk about the dynamic between you and Michael Malarkey as Quinn.

Yes, that's a fun relationship, and I'd like to think we're not overdoing it, that we're not going for the absolute polar opposites. The characters have a lot in common and a wry appreciation of each other. It's somewhat risky to try and be too subtle with it ... but it's better than going for the obvious odd couple. And it's great working with Michael. His character is showing different colors as the episodes go on and it's been nice to watch.

And now this shady Susie is going after Quinn, as well. The woman is clearly interested in completely infiltrating your life.

Yeah. I think we all have our ideas of where she's coming from as far as the spying and the espionage and the Russian aspect of it ... as a period piece, we're well aware of the paranoia that was prevalent then. It was very much in the air for the Americans regarding the Russians.

And all of the military stuff makes you wonder what else has been hidden from us over the course of the last six decades.

I think governments will always be covering things up. It's in their interests, and they'll get away with it by saying it's in the interest of the people. Which is why Hynek is just fed up. He's trying to explain these [UFOs] away so there isn't mass hysteria. But there was less scientific know-how then to be able to explain it away and quite a lot of post-war fear and paranoia. Back then, it was probably a wise thing for any government to try and get the experts in to explain that [they're] just the Northern Lights or birds.

It provides some kind of reassurance.

Yes. Unfortunately, everything couldn't be explained. It probably stoked imaginations that were really running wild with this stuff. But even beyond that, some of the stuff is genuinely inexplicable to people with very reasonable, logical thought processes.

There are some things that we'll just never know. Has doing Project Blue Book led to people just coming up and telling you their experiences with seeing things?

Yes, at the conventions, the Comic-Cons and stuff I attended before the show aired. Since it's started, I've been mostly in Ireland and I've been working in England. But I've talked to some people who have seen the show and I have seen some of the online reaction which has been positive. I haven't been inundated with stories because I've not been in the right place. I look forward to it, though.

Are UFO sightings as big a thing in Europe as they are in the U.S.?

There was a quite widely reported UFO sighting off the Irish coast, not so long ago, maybe in the late summer of last year. There's an audio conversation between air-traffic control and two commercial airliners. One was a Virgin Atlantic, I think the other was British Airways and air traffic control in Ireland. And also a small private plane.

It was quite fascinating to hear what they were reporting, lights streaming past planes at Mach-2 speeds and then disappearing at crazy angles. It was all over the news here about seven months ago, and the reports lasted for a couple of days. As well as being inexplicable, it's also seen as a novelty item, as well, so I don't think people feel threatened by it. They want to hear about it.

Like the Loch Ness Monster.

This is a little bit more. The Loch Ness Monster is a great story, this was actually being reported by a commercial airline pilot. They were talking about it! I think people are a little bit more inclined to just report what they see these days, like that sighting off San Diego a couple of years ago with the Air Force pilots, which had video also and audio. Who knows what these guys saw off the Irish coast, but to hear the actual conversations and see the video is quite fascinating.

Do you watch the skies a little more closely now?

Yes, but I always did. It was something I was instilled with by seeing Close Encounters as a youngster.

So you wonder what those things might be up there?

Oh, yes. We're hoping it would be something that I can't explain.

Project Blue Book will return for a 10-episode Season 2 on History, date TBD