Keiko O'Brien returns from a visit to the fire caves of Bajor... but not alone. She has been possessed by an evil entity with complete access to all her knowledge. Ahead of Miles at every turn and cutting him off from any help, the entity forces him to sabotage systems on the station for its own nefarious purposes.
Though this story was initially pitched by outside writers as more of a hostage situation, staff writer René Echevarria turned it into a creepy tale of possession, adding the notion of "evil wormhole aliens" so that it wouldn't just be a random entity. Their name, though, came from another staff writer, Robert Hewitt Wolfe, who'd actually had the same rough notion for Bajoran "devils" clear back in season one, only to have his reference to "pah-wraiths" cut from the final script.
Neither writer is credited for the script here, though. With all hands on deck to create the 30th anniversary episode "Trials and Tribble-ations," show runner Ira Steven Behr invited then-freelancers Bradley Thompson & David Weddle, whose season four pitch had worked out, to help here. By the end of the season, they'd be offered positions on staff.
Keiko's possession is a chilling idea even on paper. No one knows Miles O'Brien better than his wife, keeping the entity ahead of him at every turn. The pah-wraith threatens the lives of his loved ones to keep him in line, in ways both subtle (roughly brushing Molly's hair) and overt (forcing Keiko to dive off the promenade balcony). But the cruelty is constant, and no torture seems too small for the pah-wraith to inflict. It forces Miles to sleep in the same bed, sends him through the motions of a surprise birthday party, even makes him give "her" a kiss when people are watching.
This all becomes better still in the execution, though, thanks to a fantastic performance by Rosalind Chao. She isn't often given a lot of meat as Keiko, and her role in most episodes is sweetness and charm. Suddenly, she's in a dark and sinister gear, tossing off threats with casual disdain, and indulging in the pleasures of having a flesh and blood form. She switches back and forth on a dime, bringing full evil to the fore when only Miles is there to see it, and disguising it when others are around. Rosalind Chao was reportedly one of the actresses in the running to play Tasha Yar on Star Trek: The Next Generation, and from this episode, I can actually see it. She's forceful, badass, and in charge... and it's fun to watch.
That excellent performance also brings out the best in Colm Meaney, who's great as the tortured Miles. Most of his key moments in this episode are conveyed only with a look -- staring daggers as he makes a birthday wish, turning aside an earnest offer of help from Worf, realizing how he might use Rom to get through it all, and ultimately being caught red-handed by Odo. There's a reason why Deep Space Nine made it an annual tradition to make Miles O'Brien suffer; they knew Colm Meaney would always deliver.
It's also a strong episode for Rom, as he strives to fit in at his engineering job. He wants whatever breakfast his co-workers are having (much to Quark's disgust), is eager to fill in for someone who's out sick, and is trying his best to please his boss. But it's another "Rom is no dummy" episode, as he figures out what the pah-wraith is really up to, and stoically plays dumb to Odo when O'Brien throws him under the bus. ("I'm Quark's brother. I know the role.")
Other observations:
- There may have been references to it before this episode, but the phrase "waste extraction" really stuck out to me this time. Waste extraction? Is that like using the transporter to beam the poop out of people?
- This episode was actually filmed after "Trials and Tribble-ations," but aired first (probably because of all the visual effects that had to be completed for that episode). As such, Nana Visitor was in the final days of her real-life pregnancy, and unavailable for this episode. It's too bad, as I think getting Kira's thoughts on the pah-wraiths would have been a nice texture for this episode.
- This was the first time Allan Kroeker directed an episode of Star Trek. He'd go on to direct over three dozen episodes across Deep Space Nine, Voyager, and Enterprise -- including the series finale of all three.
- Miles and Keiko now share the experience of being possessed by malevolent aliens. In the Next Generation episode "Power Play," the roles were reversed.