Star Trek: Discovery wraps up its third season — and its three-part season-ender — with “That Hope is You, Part 2,” a finale that ties up loose ends, opens new doors, and sets the Federation on the path to peace and cooperation.

WARNING: MAJOR SPOILER ALERT!

Picking up where “Su’Kal” left off two weeks ago, the story on the dilithium planet remains focused on helping Su’Kal (Bill Irwin) confront his fears and encourage him to disengage the holoprogram that’s preventing him and the Discovery away team from leaving.

As with the other crewmembers who beamed down to the planet, Adira (Blu del Barrio) and Gray (Ian Alexander) — who is recognized, apparently, by the holographic environment as an individual — are both given a different alien appearance. Adira gets the guise of a Xahean like last season’s Queen Po, and Gray manifests as a Vulcan… and as good as Gray looks as a Trill, he looks amazing as a blue-haired Vulcan.

While Saru (Doug Jones) stays with Su’Kal — eventually helping him understand his life, his past, and preparing him to go “outside” — Dr. Culber (Wilson Cruz) works with Adira and Gray to determine the state of the crashed Kelpien ship, and finally crack the mystery of how Su’Kal caused The Burn.

Yes, it was Su’Kal: specifically, the connection between his DNA and the high concentrations of dilithium found on the planet, the result of his long exposure to the radiation, and the hostile environment. As Adira explains, dilithium has an inherent subspace component, allowing Su’Kal’s outbursts to propogate across interstellar space to affect dilithium across vast distances.

This also explains the limitations in subspace communication that accompanied The Burn; if Su’Kal can be evacuated from the planet, before another emotional explosion, any future Burn-like events will be prevented.

Finally — though not a lot of time is able to be spent on it — Adira and Gray’s time in the holoprogram allows Gray his first experiences as a separate, visible individual since his death. Culber and Saru are able to see and interact with him, and it’s tragic that he will again cease to be corporeal once they evacuate from the planet.

Culber’s promises that they’ll work to find a solution — such as the Doctor’s 29th century mobile holo-emitter, now “old” tech to the Discovery era — has me optimistic that a solution is forthcoming. Gray as an individual deserves to exist and be seen, as do Adira and Gray as a couple; we’ll have to put a pin in that story, however, until the pair returns next season.

Back at Federation Headquarters, an unnervingly close-quarters firefight breaks out between the Emerald Chain-held Discovery and the ten or so large Federation ships within the shield barrier. Impressively, Discovery is able to withstand the several-minute barrage of phaser and torpedo fire with little damage; perhaps even more impressive is that none of the other ships are accidentally destroyed by the crossfire.

It’s not until an entire fleet from Ni’Var arrives at Headquarters’ doorstep to help — called into action by Burnham’s mayday message last week — that Chain’s green leader gets desperate.

To force an end to a firefight that has just escalated beyond what is winnable, Osyraa (Janet Kidder) threatens to use her stockpile of potent pesticides — established in “The Sanctuary” — as a makeshift means of chemical warfare. Horrified both at the potential loss of life and that she’s indirectly dragged Ni’Var into the conflict, Michael Burnham (Sonqeua Martin-Green) convinces Admiral Vance (Oded Fehr) to let Discovery and the waiting Viridian leave Headquarters for the safety of a nearby Emerald Chain base.

Once on the way, Osyraa brings Burnham to witnessed a captured Book (David Ajala) in sickbay, where Zareh (Jake Weber) has been threatening to torture him for the coordinates of the dilithium planet. After a few minutes of especially painful torture, Burnham manages to rescue Book and the two of them escape.

Continuing the Die Hard homage seen in “There Is A Tide…,” turbolifts and turbolift shafts — er, chasms — take the place of elevators as Burnham and Book attempt to elude Zareh and his Regulators. Climbing into (and eventually on top of) the turbolift cars, the heroes get separated while fighting a group of bad guys.

Book struggles with Zareh in a rocketing turbolift car, until he’s finally able to toss him to his death below. As with “Part 1,” one of the lessons to be learned from “That Hope is You, Part 2” is that if you’re ever in a fist fight with Cleveland Booker, you absolutely do not want to insult his cat.

It is completely irrelevant to the success of this episode and does not meaningfully subtract from how fun and well executed the turbolift fight sequences are, but I do have to take a moment to ask how there’s an entire Blade Runner cityscape housed within Discovery’s secondary hull.

We’ve seen the turbolift “roller coaster” before — and it’s always been confusingly large — but “That Hope is You, Part 2” turns it into a truly cavernous space that extends all the way to the horizon. Frankly, I just don’t get it (unless Starfleet uses TARDIS technology in the 32nd century), but ultimately it’s not going anywhere any time soon, so perhaps I should just get over it.

Meanwhile, acting captain Sylvia Tilly (Mary Wiseman) deciphers a message from Burnham, which originally seems like a random reminiscence about a birthday celebration the two women shared but is actually a message encouraging the crew to sabotage a warp nacelle. If they can build a device to disrupt the magnetic attachment between the hull and the nacelle, the ship will drop out of warp.

Easy enough, except that oxygen levels are quickly depleting and the crew can’t use a DOT-23 drone to get the job done. Luckily, Lt. Owoeskun (Oyin Oladejo) can hold her breath for a very long time. Owosekun is successful, and Discovery is forced out of warp.

This bit of backstory, that she spent her childhood freediving for abalone, is so specific and suddenly offered that it’s painfully obvious as a setup for something later in the episode, but Owosekun is such a cool character that I genuinely don’t care. It’s clunky as hell, but any opportunity to learn more about her — no matter how situationally convenient — is fine with me.

Instead of the task being a suicide mission, thankfully Owosekun is rescued by one of the three Zora-possessed DOT-23’s. While I am eternally grateful to the Sphere Data droid for saving Owo, this is as good a time as any to say that I don’t particularly care for the deliberately cute design of the robots — especially given that they exist first and foremost to be functional repair robots.

They have the distorted proportions, tiny hands, and big wide eyes of a Funko POP! doll or Baby Yoda. This is 100% a subjective thing, so don’t get all worked up if you disagree, but I would like this version of Zora much more if it had used something like the trio of abstract looking flying robots Reno built during her time stranded on the crashed Hiawatha.

Reno’s “kids” were expressive and interesting without relying on the kawaii anthropomorphism of big blinking eyes and looking cute. But that’s enough of me being grumpy in the face of the adorable.

The showdown between Burnham and Osyraa in the data core goes by pretty quickly, both characters much more interested in an efficient conclusion than monologuing to one another.

In an unusual choice, Osyraa attempts to kill Burnham by pushing her into a wall made of the same type of programmable-matter computer interface we’ve seen on Book’s ship. Burnham is completely submerged (shades of Superman 3), but quickly shoots her way out, hitting and killing Osyraa in the process. I wonder if this was something that maybe worked better on the page; on screen it just elicits an anticlimactic “huh.”

As soon as Osyraa is out of the picture, Burnham regains control of the ship, restoring life support and saving the remaining crew by beaming the Regulators “off the ship.” And directly into space? Sure maybe, works for me.

Once everyone meets on the bridge, Tilly immediately hands command over to Burnham. I was skeptical when Saru chose her to be his second in command, but that skepticism disappeared the moment she confronted Osyraa in “Su’Kal.” Tilly was calm, collected, and capable, a great captain for her ship and leader for her crew. That she would so quickly relinquish something that she’d been so successful at was disappointing; I hope we get some more insight into her decision later.

Knowing they need to get back to the dilithium planet ASAP and needing to blast their way out of the Viridian –which had enveloped Discovery after the latter ship dropped out of warp — Burnham’s plan is to eject and detonate the warp core then do a split-second jump to the Verubin Nebula using Book as the spore drive’s navigator.

The plan is risky and Book has never even touched the spore drive before, but it works. The fact that Book is able to use his empathic abilities to successfully operate the spore drive does open up the question of whether other members of his species would be able to do so as well.  Hmm…

Back in the nebula, the away team and Su’Kal are rescued just in the nick of time and Discovery returns to Federation Headquarters.

With Osyraa’s death and the destruction of the Viridian, the Emerald Chain seems to fall apart and no longer seems to pose any significant threat to the Federation or to various peoples and worlds, leaving Starfleet to mine and distribute the newly discovered dilithium cache without interference. The Federation also appears to be on the path towards at least some level of reunification: Trill has already rejoined, and Ni’Var is considering it as well.

Saru, who goes an extended sabbatical to Kaminar — to help Su’Kal settle into life in the real world — is now unavailable to captain Discovery, giving Admiral Vance the opportunity to extend to Burnham a captaincy that, despite their earlier conflicts, he truly believes she’s earned. After a bit of hesitancy, wanting to discuss the situation with Saru first, she accepts after Vance demands an immediate answer: after three years, Captain Michael Burnham takes the center seat.

In addition to this major change of command, many viewers will surely also be glad to see that the Discovery crew is also leaving on their next mission with some shiny new uniforms! It appears that going forward the crew will be leaving their 23nd century blues behind for the predominantly gray uniforms seen on the rank and file of the 32nd century Starfleet.

It should be noted as well that based on their uniform, Adira has gotten their own commission into Starfleet — assigned the rank of Ensign in the blue-stripe science division — and Book, though still dressed in his civvies, appears to be staying aboard as well. Book and Burnham are excellent together and I would miss them next season were Book not to stick around.

OTHER OBSERVATIONS

• Doug Jones is up in Toronto filming Discovery Season 4 right now, so don’t expect Saru to be out of the picture next year.
   
• Was it concerning to anyone else that the Crossfield-class warp core ejection system includes shooting the thing down a long tube without any stabilization, letting it bang and spark off the sides of the ejection tunnel the whole way down?
   
• The theme music played over the end credits is, of course, the same classic tune which closed out every episode of the Original Series. (Sadly, there’s no Heather Kadin credit over a dancing Orion, or CBS Television Studios logo over the fake alien from “The Corbomite Maneuver.”)
   
• Cleveland Booker isn’t the first person to carry that name, nor does that seem to be our Booker’s given name. He mentions a mentor by that name, a person he hoped to live up to when he took the moniker. This story, sure to be part of Season 4’s tale, is likely to explain some of Book’s still-not-totally-explained origins, specifically how someone who doesn’t seem to be human has such a human sounding name.
   
• I was extremely happy to see that lonely Aditya Sahil (Adil Hussein), who manned the long-isolated Starfleet watchtower in the season premiere, finally found his way back to the Federation after years of service in isolation… now an officially-commissioned Lieutenant.
   
• In keeping with sacred Star Trek tradition, the dialogue for “That Hope is You, Part 2” includes mention of an “alien adjective animal”: the Alcorian Sorrowhawk, first mentioned back in “Calypso.” Not quite as catchy as the Tarcassian razor beast Denebian slime devil, but still pretty good.

• We learn from Osyraa that Orion hearts have six valves and that “blood flows in both directions.” I’m Hoping a xenocardiologist can shed some light on this because that sounds bad to me, from an oxygenation standpoint.
   
• According to Su’Kal’s holoprogram, the gormagander has the dubious distinction of being the animal that’s spent the longest amount of time on the Federation’s endangered species list.
   
• Though we don’t see him joining Discovery on its mission to distribute dilithium, Aurellio did survive Burnham’s order to beam all Regulators off-ship. Technically he wasn’t a Regulator, but as a member of Osyraa’s party the computer could reasonably have interpreted him as being included in the command. Glad he didn’t get spaced.
   
• While Stamets is back on board under command of Captain Burnham, it’s clear that he’s still not cool with her blowing him into space and leaving Culber and Adira to (potentially) die. That friction should be interesting to see play out next season.
   
• Finally, CBS shared artwork, class names, and registry information of several 32nd century Starfleet vessels this week; The Trek Collective has pulled together a great walkthrough of the different inspirations for ship names and class designations.

Closing out the season, Discovery leaves for its humanitarian mission under newly minted Captain Burnham — “Let’s fly!,” landing on a catchphrase right from day one — and the episode ends with a quote from Gene Roddenberry:

In a very real sense, we are all aliens on a strange planet. We spend most of our lives reaching out and trying to communicate. If during our whole lifetime, we could reach out and really communicate with just two people, we are indeed very fortunate.

After three seasons filled with drama and conflict, and three action-packed episodes to close them out, it’s extremely satisfying to end the year on a quieter note of optimism and adventure. Instead of spending its final ten minutes setting up the next Big Bad or insinuating that all is not what it seems, “That Hope is You, Part 2” simply breathes.

And that, as backward as it may seem, has me more excited for what’s to come in Season 4 than any cliffhanger.