Thursday's episode of Grey's Anatomy featured the best twist on the show since "The Man Hit by the Bus Is George." And no, we're not talking about the fact that Owen's (Kevin McKidd) sister Megan is actually alive (more on that later).

Stephanie (Jerrika Hinton) may have just made a very fiery exit from Grey's, after being taken hostage by a psychotic patient and inadvertently causing a gas tank explosion. We'll have to wait until next week's finale to find out for sure whether Stephanie's a goner, but it's not looking good.

Here's how it all went down: Stephanie breezes through her mandatory counseling and returns to Grey Sloan just in time to pitch in on the case of a young couple brought to the hospital in bad shape after their car somehow rolls off a cliff while they're hooking up in it. They both ask for each other as soon as they wake up, but can't stay conscious enough to explain the full story. So the doctors start taking bets on whether this is the most romantic couple of all time, or just a random hookup.

As it turns out, it's neither — and things go downhill from there. Once the girl, Alison, regains enough strength to speak to the doctors, she says that the man in the car was a stranger who was trying to rape her, and she stepped on the gas on purpose to send the car off the cliff. Her asking "Is he dead?" earlier wasn't a plea for her lover, but a question of fear.

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Once Bailey (Chandra Wilson) and Jackson (Jesse Williams) realize what's going on, they call the police in, and Jackson remembers that he left Stephanie alone with the patient. Unfortunately for Stephanie, he's already won her over her with a story about needing to be there when his "girlfriend" wakes up, so she's in the process of sneaking him down to the ICU.

They run into doctors whispering about a rapist in the hospital, and before Stephanie can put two and two together, the patient has a scalpel at her throat. He forces her to walk down the stairs with him so he can escape, but before he makes it out the door the hospital goes into lockdown, so they're trapped — along with a child named Erin (played by Big Little Lies' Darby Camp) who's running wild in the hospital while her baby sister gets treated in the ICU. Stephanie makes the mistake of telling the patient that the only way the doors are going to get unlocked is if the lockdown is called off, or if emergency services need to get through "in case of a fire or something."

So the patient goes to work trying to light a rag on fire, after Erin helpfully hands him a Bunsen burner lighter. As he's waving the rag near the sprinklers, Stephanie picks up the lighter fluid and douses him with it. (Why she opted to do this instead of picking up the scalpel from the floor and stabbing him with it, we'll never know.) And so a cinder from the rag ignites his whole body, and Stephanie pulls Erin into a room for safety...

Only not. As he's writhing around, the patient rolls in front of two huge gas tanks. Stephanie runs into the room — why? to try and pull him away? — just as the whole thing explodes.

And that's not all. Meredith (Ellen Pompeo) witnesses the whole shebang (literally) because she's on her way home to inform Nathan (Martin Henderson) that Megan is, in fact, alive. At the beginning of the episode, soldiers show up at Owen's door and inform him that Megan was found in the basement of a house in a rebel-held neighborhood. That triggers Owen's PTSD and he at first denies that it's her, but after Amelia (Caterina Scorsone) gets confirmation from Teddy (!) and requests that Megan be sent immediately to Grey Sloan, Owen finally accepts it. Now he just has to grapple with the guilt he feels for giving up on searching for her and sometimes going days without even thinking about her while she was being tortured in a basement.

And, that mysterious phone call that Alex (Justin Chambers) was making at the end of last week's episode? It was to a private investigator, to track down Jo's husband — which he does, to a conference in LA. After imagining a number of fantasy scenarios that involve him either threatening Jo's husband (played by Matthew Morrison) or beating the crap out of him, what actually happens is... nothing. At the end of the day, "Paul" inadvertently steals the cab Alex is trying to hail, but then offers to share it with him to the airport. But Alex declines and says he'll grab the next one.

So what do you think, Grey's fans? Is that the last we've seen of Stephanie Edwards? Should Alex have said something to Jo's husband? And were you shocked by the reveal that Megan's alive, or did you totally see that coming? Sound off in the comments!

The Grey's Anatomy Season 13 finale airs Thursday, May 18 at 8/7c on ABC.