For a show called Star Trek: Discovery, they do like to keep things mysterious. CBS All Access' reboot of the venerable sci-fi series will launch on Sept. 24 (it will also broadcast its first episode on CBS, before moving full time to the streaming service), yet not much is known about the plot. And when TV Guide visited the set of the show in August, one of the most frequent phrases we heard was, "we can't tell you that."

Despite all the secrecy, there are some facts we do know. The series is returning 12 years after the last TV expedition, Star Trek: Enterprise. It's set approximately 10 years before the original series, which starred William Shatner and Leonard Nimoy, and focuses on the start of a cold war between the human led Federation, and the often villainous Klingons, before they became the Klingon Empire and one of the main antagonists of multiple series and movies.

And speaking of movies, this series takes place in what's called the Prime timeline, meaning it will not reference or tie into the relatively recent movie reboot, which takes place in what's called the Kelvin timeline. As we (sorry) discovered, the show won't contradict the movies in any way, but at the same time will very much follow its own path.

Oh, and for the first time its star is a woman who is not the captain of the ship. The Walking Dead's Sonequa Martin-Green won't be taking the helm, but she will be anchoring the cast as Michael Burnham, first officer of the Federation ship USS Shenzhou, raised by Spock's (Nimoy) father, who transfers to the Discovery for — you guessed it — mysterious reasons.

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The show also stars a bevy of recognizable faces, including Jason Isaacs as Captain Gabriel Lorca of the Discovery, who has secrets of his own; international superstar Michelle Yeoh as Philippa Georgiou, captain of the Shenzhou and Burnham's mentor; Doug Jones as Saru, the Discovery's science officer and new type of alien called a Kelpian; and Anthony Rapp and Wilson Cruz as Paul Stamets and Hugh Culber, the first openly gay couple in Star Trek history.

There's a lot more we learned while on set — and a lot that stayed secret, as co-showrunner and executive producer Aaron Harberts toured us and other press outlets around the massive sets of Discovery. Here's everything we learned — and a few secrets we can't tell you yet:

Jason Isaacs as Captain Gabriel Lorca, Star Trek: Discovery Photo: Jan Thijs, CBS

1. Lorca isn't your run-of-the-mill captain.

Beyond his dark disturbing secrets — and we've got some theories on those we'll share at a later date — Jason Isaacs' Lorca isn't your typical Starfleet captain. That starts with his allergy to chairs. Where previous captains like Picard (Patrick Stewart) and Kirk (Shatner) spent a lot of time in the captain's chair, or in their office (more on that in a second), Lorca will spend a lot of time down near the viewscreen. This was a choice Isaacs made, presumably to give the very physical actor more room to play and engage with the rest of the cast.

2. The tech isn't stuck in the '60s, but it does pay tribute.

Despite taking place pre-Original Series (aka ST:TOS), the tech has been updated to reflect a more modern aesthetic. "We are living in present day language of what the future is bringing us," Harberts noted while standing over the Discovery's communication station. "But also firmly nestled in those ten years before the original series."

That means there are the buttons and knobs omnipresent in ST:TOS are still there on the consoles, but as part of a slicker design. And the displays are cutting edge (for 2017, at least): they're real television screens that haven't been released in stores yet. The screens go completely transparent, and are loaded with graphics that play in time with the action (since the TVs aren't touchscreen enabled).

3. ... But the buttons are touch enabled.

This came as a surprise as one of the other outlets on the tour touched a button on Lorca's captain's chair, expecting nothing to happen. Instead, a small viewscreen built in to the arm of the chair swiveled upwards, so the captain can deliver an address to his crew. Aside from the alarmed production staff and surprised press members, what's most impressive is how practical the sets are. They aren't all actors hanging out on green screens, and digital touches later in post. That's there, and the team does utilize digital techniques — but as much as can be practical and interacted with on set, is.

4. Diversity, diversity, diversity.

When producer Bryan Fuller came on board Discovery, one of his biggest pushes was to keep the sense of forward movement in casting and diversity Gene Roddenberry's original vision brought to Star Trek. Fuller eventually left steering the ship full time, in favor of showrunners Harberts and Gretchen J. Berg, but that push remains.

It starts with the main cast, of course, but continues with the day players: Harberts noted that he's "very proud" of the incredibly diverse Toronto-based actors they've brought in to fill out the bridge of the Discovery (as well as the other ships). "It's amazing the depth of talent we've been able to mine here," Harberts added.

5. Lorca would prefer to stand, thank you.

When he isn't lurking at the front of the bridge by the viewscreen, Lorca is in his office, which is physically connected to the bridge set to allow for seamless camera transitions. And no, he's not going to sit down in there, either. Lorca has a very au courant standing desk, which Harberts noted allows Isaacs to have a, "more commanding physical presence... It adds extra weight to a character who has a ton of secrets and mystery around him."

Isaacs initially wanted an elevated desk on a platform, instead of a standing desk — but the low ceiling meant his head would be constantly getting bonked, which does not add to one's air of mystery.

6. War! What is it good for? Battle maps, mainly.

The rest of the office is outfitted with some ominous touches, including a Klingon vs. Federation War battle map, which will be updated every episode — and includes plenty of Easter Eggs for fans to still frame and sit through (we noticed a few extremely deep Trek references we won't spoil here, in case they do play into the series).

And though the war will play heavily into the show, and is a large part of the planning Harberts and team have been doing episode to episode, the showrunner wanted to be clear on one point: "We're really trying to make sure that people understand it's a grim prospect. As Georgiou says in the pilot, 'wars are screams and funerals.'"

Harberts noted that's not a direct quote, but that her perspective on war is the one he thinks viewers should take when they approach the show.

7. Show me onscreen is so several series ago.

Since the very first episode of Trek, captains have been asking their crew to "show me onscreen." And while that may still happen in Discovery, there has been a, uh, 2254 update: holograms.

"What allows for us is to have two actors in a room, playing a scene," Harberts said. Instead of pointing to a blank wall, with footage being filmed on a separate stage and added later, the "hologram pedestals" are filmed concurrently, allowing for more "energy" on screen as the actors interact.

The holograms will also be used Iron Man-style, with blueprints of ships brought up allowing the crews of the Discovery and Shenzhou to play with them and spin them around.

8. For a space show, it's surprising natural.

At least when it comes to the lighting. Though of course the production utilizes external lights when shooting, "the cinematographers really wanted to make sure there was as much sourcing as possible," says Harberts. Meaning from the hallways to the ready rooms, to the deck of the Discovery itself, lighting is built in where it would naturally occur. This, of course, saves time in the production; but also leads to a more realistic feel to the show, versus the "stage" feel of much of the original series, and Star Trek: The Next Generation.

"Our DPs [directors of photography] are going for this rich, almost Rembrandt texture," Harberts added.

Michelle Yeoh as Captain Philippa Georgiou, Sonequa Martin-Green as First Officer Michael Burnham, Star Trek: Discovery Photo: Jan Thijs, CBS

9. And there's a reason everything is so gray.

No, this isn't a space set tribute to 50 Shades. Instead, they tried adding more color into the sets, starting with some brick red hexagonal pieces on the Shenzhou. Immediately, the sections felt out of place and popped out, glaringly contrasting with the Starfleet issue look of the rest of the ship.

"When you start introducing color into sets like this it draws attention to itself," Harberts said. "Color is a great way to express ones self, but suddenly you're seeing pow, it's red."

10. The Discovery set was almost two stories tall.

Initially the plan was to have the Discovery set not just continue horizontally, but vertically as well. Ultimately, having a second story below the main bridge was deemed too expensive, and the plan was scrapped. "Maybe in season five," Harberts joked.

11. Bridge to engineering, bridge to engineering.

Though time will be spent on the bridge of the Discovery, the focus on Martin-Green's Burnham doesn't just extend as far as her title. Burnham's main area of operation is engineering, and a good chunk of the show will be spent in the below-deck room. Burnham is paired with Cadet Tilly, played by Mary Wiseman, and Stamets, who runs the room and attached lab.

Engineering is important as a focal point of Burnham's life and career, but there's also a — you guessed it — mysterious reason for the room, all focused around a series of canisters embedded in the wall. Harberts paraphrased a line from Lorca, saying, "we're coming up with a new way to fly" — and these canisters, and what the engineering team is working on, are a key part of the plot.

Just off engineering is the warp core (or at least, a small piece of the warp core, to give the suggestion of the massive engine that propels the Discovery), as well as another room that is vitally important to the third episode of the fledging season. How? "It's a mystery," said Harberts.

And in engineering itself is something called "the reaction cube," which plays a big part in the first season of the show, and provides "a lot of different types of reactions," Harberts said, vaguely. Yep: it's a mystery.

13. Want chili peppers on the Discovery? You're in luck.

Just off of engineering is an area with a wide range of samples used by Stamets, who is an astromyscologist (someone who studies space fungus). The shelves hold a mix of prop elements, and actual dried food items like chili peppers and mushrooms. "Who's to say that shitakes and criminis aren't important to Stamets?" Harberts joked.

14. Stamets and Culber are a normal couple.

Touring the quarters of Discovery's ground-breaking LGBT characters, you'd be forgiven for thinking, "well this isn't such a big deal." But that's the whole idea.

"They're just a couple like any other couple," Harberts noted. "For me that meant showing a couple doing what couples do. Which is why we had to show the bathroom. They will do a lot of toothbrushing, and downloading on the day."

He added that yes, they do have toothbrushes in the future — though, "like the Brady Bunch, there's no toilet."

The goal with the Stamets' room was to make it feel lived in, with a few personal items around. Each quarters will be a little different — for example, Burnham uses Starfleet issue sheets, while Harberts joked that the Stamets had stolen their fur top sheet from Game of Thrones.

On the other hand there's Silvia Tilly, who has some "strange sleeping habits." What they are, you'll just have to tune in to find out.

15. They use every part of the space buffalo.

Nearly every set we saw doubled as another set. The airlock has a lift that takes you to the saucer section of the Discovery, but it also doubles as an armor room. Engineering was originally a torpedo bay. The hallways turn over from one ship to another, a process that takes nearly a week (more on that later). And brig doubles for...

16. Lorca's menagerie.

Though he declined to elaborate too much, Harberts told the group that the brig is also referred to with the very evocative name "Lorca's menagerie," adding that he, "is a student of war, in addition to being a Starfleet captain." Lorca will spend time on the deck of the ship, and in his office — but given this is a secure access room, a lot of his work will happen in the menagerie. Whatever that means.

17. Let's talk about hallways.

Star Trek: The Next Generation had a lot of things going for it, but one of those things was not multiple hallways. The show famously had one hallway set, that would be repeatedly filmed from different directions to make it look like the ship was bigger than it was. Not so with Discovery, which has a stunningly long hallway set that stretches, twists, branches off and has multiple contiguous rooms attached to it.

And in fact, as mentioned above, the halls of the Discovery double as the halls of the Shenzhou. It's not as simple as switching lighting back and forth, though that's part of it. The process can take up to a week for production to switch over from one ship to another. "It's something that has to be contemplated very seriously," Harberts said of the switch. "It's unlike any other show I've ever been on."

Part of the difficulty? The hallways aren't all cardboard and easily destructible props. They're solid, made of metal plates, plastics and painted wood. So ultimately what's being reused is the frame, while the rest of the hall changes. Take that, Enterprise D.

18. Harbert's favorite set is the mess hall.

We weren't able to see the dining room set because it was being switched over itself, but Harberts credited it as his favorite mainly because, "you get a sense of a ship with all different people."

19. The Shenzhou is not your typical starship.

The bridge of the Shenzhou is an "underslung" bridge, which means the bridge is on the underside of the saucer section. Because of this, there are battleshields — screens that deploy over the windows — on the bottom of the ship, which becomes a story point in the second episode.

It's an older ship, more in common with ST:TOS' ships than the modern/mixed ships seen elsewhere in Discovery. And where the ship Discovery is a science vessel conscripted for war, so it feels a little more hopeful — there's an "intensity when you step on this bridge," says Harberts, referring to the Shenzhou. The bridge is more cramped, with sunken areas... More akin to a submarine out of Hunt for Red October than the spaceships we're used to from other Star Trek series.

It was also a very different shooting experience. Where the Discovery is wide, open, and walkable; due to the sunken nature of the Shenzhou, access to the deck is at the top of an extremely tall staircase that multiple actors and crew members tripped on during filming. The directors and producers would sit on the soundstage floor, and then would have to climb up to give notes. "I think this is why I lost 5 pounds," joked Harberts.

Michelle Yeoh as Captain Philippa Georgiou, Star Trek: Discovery Photo: Jan Thijs, CBS

20. Georgiou is also not your run of the mill captain.

Yeoh picked out the decoration for her own ready room, including Malaysian puppets, and a — get ready for this killer Easter Egg — bottle of Picard wine. Chateau Picard is a real wine in the real world, but also exists as a vineyard in the Star Trek universe, maintained by Captain Jean-Luc Picard's ancestors (and has made several memorable appearances in The Next Generation). Hopefully it's placed right next to a bottle of Michelob, the beer Kirk tried in Star Trek IV: The Voyage Home.

21. Speaking of bottles, yep, there will be bottle episodes. Sort of.

"Bottle" is a term used by the industry to describe episodes that take place entirely (or mostly) on one set. It's a cost saving measure, and why you'll usually see at least one episode of a sitcom where the whole gang gets trapped in an elevator. Discovery isn't immune to the bottle episode, but Harberts added that it's not the traditional way of tackling the concept.

"We will do two or three, primarily what you would call bottle episodes," Harberts said, clarifying that to him they're episodes that all take place on the multiple sets of the ship. "But not anything as bottle-y as 'everyone is stuck in the mess hall!' Though I'm sure production would like that."

22. We watched a scene get filmed.

Ready to get frustrated? The assembled press watched a scene filmed for an upcoming episode... But that's all we can tell you about who was in it, the plot, the dialogue — basically anything about the scant seconds, which were broadcast from another soundstage to a few rows of seats placed in front of the set of the Discovery.

Here's what I can tell you: the shots were gorgeous. You've been able to see the stark lighting and stylish sets — which Harberts noted were inspired by brutalist architecture — and that continues well into the series. Harberts himself, when we discussed the shots later, seemed in awe of the crew's use of lighting and set, as well as framing of shots more in line with a feature film than the Star Trek shows of the past.

23. They're not done yet.

Before we left, we were ushered on to a new, massive set that won't be revealed until towards the end of the first season. Yeah, we're being big mysterious jerks here ourselves, but suffice to say it's a huge spoiler for what happens later in the series. But the main reason for showing this off? "We will continue to be building sets," Harberts said, "don't tell our line producer that - until the bitter end."

Star Trek: Discovery premieres Sunday, Sept. 24 at 8:30/7:30c on CBS before moving exclusively to CBS All Access.

(Full disclosure: TV Guide is owned by CBS)