"If this were a horror movie, I'd say don't go into the house."
REVIEW: The Kaylon threat has united the Union and the Krill, which has opened up new avenues of exploration normally cut off by Krill territory. To negotiate the details of the corridor to the targeted Naklav Sector, the Union sends in Admiral Paul Christie who, as it turns out, was briefly married to Dr. Finn after an inappropriate university romance (him a teacher, her a student). He's the one who left, but 25 years later, he regrets it. She doesn't. As subplots go, this is pretty standard, but it's fairly well done. As to why this guy is then ON the exploration mission (which could technically last months), that's just one of many plot holes plaguing this episode.
It's pretty obvious why the Krill would let the Union have this particular sector. The beautiful, colorful bit is all old stars and uninhabited planets. And then the Kalarr Expanse is, according to their holy text, a realm of demons who possess your soul and from which ships never escape. The Union still wants to check it out, even though it's a dark patch with no stars, and when they get a distress call from inside, they immediately choose to disregard the Krill's warnings. That's fine, it's what heroes do, and it leads to some pretty beautiful imagery thanks to shadowy lighting both inside and outside the ship and cool effects. Even the music in this episode is Trek movie-quality. Aside from some gooey CG fights with the aliens, I really have no complaints regarding the production values of Shadow Realms.
But the story... So Admiral Christie is - again for no discernible reason - on the away team to the alien station broadcasting the distress call and gets infected with something that turns him into a spidery monster that then starts infecting others, puts main power offline, and calls others of this species for a pick-up. A pretty generic Trek plot, which the Orville usually manages to find an original hook into. Usually. When the lights go out, turning the ship itself into a "haunted house" (or an Aliens film), I was immediately struck by how empty it was. Though later a number of crewmen have been turned into "demons", even early on, the halls are empty and people only cross each other's paths when necessary according to the script. Where IS everyone? Finn's kids get into a bit of trouble, but this is a Finn-centric episode. Bortus' family doesn't even spare a word, comparatively. So while putting a lot of people in view would have taken away from the atmosphere, it feels very contrived that we don't.
And as we knew would happen, it's all down to Claire to talk her ex-husband down and offer him a compassionate ultimatum - leave or be destroyed by a synthetic virus - and he chooses to leave after trying to call her bluff and failing. They use his wedding ring to track him, but missed a trick in not having him discard it for Claire to figure out he had lost his humanity. But that's the least of the ending's problems. Because despite this season sporting often too-long episodes, this is one of the shortest and still manages to end abruptly, with its audience wondering just what happened. The Christie demon says he and his people will go, and we cut to epilogue. Uhm... HOW did they go, exactly? Took a shuttle? How did this play out? What about the incoming demon ships, which we never see? It's just a bit of a mess.
WHERE SOMEONE HAS GONE BEFORE: Voyager flew into a so-called "haunted" region of space in Persistence of Vision, and a vast starless expanse in The Void. The old flame and/or admiral who becomes a threat is Trek 101, of course, as are generic transformations as a way to procreate (perhaps closest to TNG's Identity Crisis here, though the spider look is more akin to a cross between Barclay's and Worf's in Genesis). The space station's shape recalls Cardassian weapons platforms.
REWATCHABILITY: Medium-Low - Generally good effects and make-up, but it offers little in the way of originality and bungles the ending.