It’s appropriate that the first part of “Terra Firma” debuts during the holiday season since the episode plays like a Star Trek version of A Christmas Carol. Emperor Georgiou (Michelle Yeoh) is our Scrooge, the grumpy, cynical curmudgeon who sees nothing but weakness and folly in everyone around her.

She too is given a grim view of things to come, albeit in the form of a bleak medical diagnosis and the prospect of an ignoble death rather than a warning of eternal damnation. But it’s enough. Just as with ol’ Ebenezer, a supernatural guide sends her on a magical journey to key moments of her life, forcing her to reevaluate past events and maybe, just maybe, achieve a change of heart that could ultimately save her.

That’s the best guess, anyway. It’s not fully clear why the mysterious “Carl” (Paul Guilfoyle) sends Georgiou back in time to the Mirror Universe, aside from it being the latest dose of “sphere data ex machina” plot development. But we do know that it’s the key to Georgiou surviving her illness, however small the chances may be, with certain hints that the trip is as much about Philippa reconciling her place in the Prime Universe emotionally as it is about finding any physical cure.

The first half of “Terra Firma” does, however, finally provide an explanation for Georgiou’s mysterious malady. As Kovich (David Cronenberg) explains, it turns out that traveling through time puts a strain on one’s molecules; traversing dimensions does the same, and doing both in quick succession can lead to a swift and ugly end.

That’s a neat sci-fi concept that leaves Star Trek with room for other universe-hopping adventures while still ensuring there’s a cost to how far from home Georgiou’s traveled over the past couple seasons. Hell, there’s even a tantalizing reference to a Starfleet officer from the Kelvin timeline (home of the reboot films) hopping over to the Prime universe and ending up worse for wear, to set the gears spinning.

But the illness itself is less important than the effect it has on Georgiou and what finding a cure requires of her. Having been given a death sentence and struggling to do basic tasks, Georgiou is even testier than usual. She rejects Tilly’s (Mary Wiseman) offer of help and knocks her lunch into her lap. She swings a blade (sadly not the Green Destiny) toward the neck of Michael Burnham (Sonequa Martin-Green), stopping just short of a kill — a gesture with a meaningful echo later in the episode.

The episode plays like a Star Trek version of A Christmas Carol.

Georgiou’s short fuse and combativeness serve two purposes in the episode. For starters, that tack continues last week’s metaphor of Georgiou as an aging parent, one who responds to newfound limitations with frustration and lashes out at those around her. Beyond that, it creates a motivating plot mechanic. Kovich explains that a dying Terran is a threat to those around them, since they prefer to die in glorious combat by any means necessary, which adds urgency to the question of “How do you solve a problem like Philippa?”

Burnham decides to cajole Georgiou into following the sphere data’s directive toward a possible cure, convincing her quasi-mom that staying put and letting the molecular disintegration take its course would turn Georgiou into a medical curiosity rather than the fierce warrior she wants to die as. The quest takes them to a snowy planet with a strange man who speaks in riddles and points Philippa through a doorway to another time and another universe.

The leap puts Georgiou back in her Emperor guise in the Mirror-verse, at a time just before the villainous versions of Burnham and Lorca would attempt their coup. A return to the harsh negative image of the Star Trek we know and love gives the audience another glimpse of that side of the divide, replete with an appearance from Captain “Killy” (as Wiseman re-assumes the role with gusto) and dark reflections of other familiar Discovery characters. As with prior jaunts to the Mirror-verse on this show, there’s more in the way of dramatics than fun here, but it’s still always a treat to see how the other half lives.

At the same time, the trip gives Georgiou a do-over. This time around, she knows with certainty that not only is Lorca plotting to betray her, but that her daughter is an active part of the plot. We learn, for the first time, that the reasons behind Mirror Michael’s betrayal weren’t just a romantic entanglement, but rather that she felt stifled living in Georgiou’s shadow and felt that her mother had grown weak. It’s eye-opening for Philippa, evoking the specters of both the Emperor’s attachment to Burnham and to the ways in which the people and principles of the Prime Universe have rubbed off on her in the years since she made the jump.

Those twin concerns seem to offer a likely destination for “Terra Firma.” In order for Georgiou’s molecules to survive the transition across temporal and interdimensional barriers, she must accept that she’s grown and even softened, that she has valid emotional attachments to the girl she rescued from a garbage heap, and that there’s a place for her in this different universe emotionally, not just physically.

In the meantime, Discovery gives us a taste of Shakespeare in the form of power struggles, family drama, and personal reflections within the more theatrical Terran Empire setting. There’s a play within a play, assassination attempts gone wrong, and questions of whether to give into the darkness or accept one’s own quiet transformation. Heavy is the head that wears the crown as Philippa weighs her options while treachery looms.

There’s more in the way of dramatics than fun here, but it’s still always a treat to see how the other half lives.

And yet, knowing where this timeline leads, Emperor Georgiou chooses to spare her daughter rather than execute her for treason. She chooses to recognize Saru (Doug Jones) and the Kelpians as, at a minimum, a resource with their own talents and value, rather than mere slaves and/or food. She takes the notions of mercy and personal connection that are otherwise anathema to a Terran, and embraces them, however fleetingly, if only to alter course from the known and terrible future she sees in front of her.

Time will tell if this second chance — of thwarted coups, spared conspirators, and hints of empathy — will be enough to move Georgiou toward a deeper understanding and better relationship with her daughter, a greater acceptance of the values of the Federation, or a solution to her condition back in the Prime Universe. The pointed conversations between her and Prime Burnham over their mutual efforts at chasing ghosts suggest there’s plenty of issues to be worked out on all fronts.

But there’s something laudable in Discovery’s creative team deciding that, if Georgiou is going to continue in this series and in this future, she and the show need to justify a transformation within the sharp-tongued warrior, one that involves processing past traumas and mistakes and coming out the other side a better person.

When Scrooge went on his own fantastical journey, the events he witnessed turned him into “as good a friend, as good a master, and as good a man, as the good old city knew.” That’s probably too lofty a goal for Philippa Georgiou at this point. But maybe sliding back into an old life that, with time and distance, no longer seems to fit her, will be enough for the Emperor to gain another chance with her daughter, and a place in her world.

Ensign’s Log:

• It turns out the distress signal from the Burn-causing nebula came from a group of space-faring Kelpiens, something that naturally piques Saru’s interest, even as he keeps it from Admiral Vance. The plot (and the Kelpien soup) thickens!
• In another nice moment between Stamets (Anthony Rapp) and Adira (Blu del Barrio), we learn that Adira’s loss of connection to Gray persists and that they feel angry and out of sorts over it, despite Stamets’s reassurances.
• Admiral Vance (Oded Fehr) gives Saru a “Don’t leave your buddies behind, or they’ll lose faith in you as a captain” speech that seems poised to become relevant later in the season.
• “Terra Firma” also checks in on Book’s (David Ajala) efforts to join Starfleet, with Saru giving his own “find your moment” speech that will also likely have a meaningful coda in future episodes.
• Incidentally, one of the ways you can tell that Saru’s growing into his leadership role is how he adopts the good ol’ West Wing walk-and-talk during that conversation.
• I initially thought that Carl, the Doorman of Doublespeak, might be a Q, but he seems to be just another intergalactic weirdo.
• The emotional goodbyes Saru and Tilly offer to Georgiou (replete with titles acknowledged and hugs returned) seem a little unearned given the brief and frosty interactions we’ve witnessed between them so far. But some great acting from Yeoh in particular manages to sell the moment.
• Here’s hoping we get a return engagement from Jason Isaacs as Lorca next week.

Star Trek Discovery Season 3 Episode 9, “Terra Firma Part 1” Trailer: