Patrick Dempsey, Caterina Scorsone Patrick Dempsey, Caterina Scorsone

We've always known Meredith Grey to be the dark and twisty one on Grey's Anatomy, but apparently she's got nothing on Amelia and Derek Shepherd.

It's Amelia's (Caterina Scorsone) night to shine (or flame out) on Grey's, with her drug-fueled past putting her career in jeopardy. How does she get to this point?

The episode kicks off with Meredith (Ellen Pompeo) apologizing to Maggie (Kelly McCreary) about the dinner party that never was. "We really lost track of time," she says of her and Derek's (Patrick Dempsey) absence, which translates (literally, a few scenes later) to "we were up having sex all night." Rude.

Quiz: Grey's Anatomy plot or Florida news story?

In another part of the hospital, Arizona (Jessica Capshaw) is indignant that Dr. Herman (Geena Davis) expects her to process in 24 hours the fact that her mentor has a fatal brain tumor. Dr. Herman tells her to suck it up. (Brain tumor or not, I still kind of hate Dr. Herman.) As a result, Arizona finds herself in the position of having to take over all of Dr. Herman's cases and also lie to the patients about why Dr. Herman is MIA.

After Meredith's sex humble-brag, Callie (Sara Ramirez) confesses that she was also up all night — but it was because she was having all kinds of feelings about her and Arizona. (Needless to say, she really doesn't want to hear about Meredith's boning-induced insomnia — but they do later bond over the "time-outs," "Band-Aids," and what have you that they've both been putting on their respective relationships.)

Amelia and Derek have a bit of a turf war over two burn victim patients who come in attached to each other on a gurney. The wife is pretty much a goner, but Amelia promises the husband she'll do her best to save her. But, when she heads out to the waiting room to update the couple's daughter, she's in for an unexpected surprise. The woman flips out and demands a different doctor. "She's a junkie," the family member blurts out as Amelia looks on, helpless and horrified. "I met her in Narcotics Anonymous ... I want another doctor." So much for Amelia keeping her past under wraps!

Grey's Anatomy's Caterina Scorsone: Amelia's past comes back to haunt her

Derek steps in to appease the patients' daughter, but Meredith later chastises him for not leaping to Amelia's defense. "The woman had it out for her, Meredith," Derek explains patiently. "If anything goes wrong, she would have blamed her because she's an addict." I'm Team Derek on this one.

Meanwhile, while Dr. Herman is AWOL, Arizona is forced to make the controversial call of performing emergency on a pregnant woman to try to save her baby's life.

Jo (Camilla Luddington) is preparing for her first solo surgery (repairing a hernia) by vomiting in the bathroom and giving herself a pep talk-slash-belittling Bailey (Chandra Wilson), who happens to be answering nature's call in the adjacent stall. Whoops!

Amelia, in the wake of the waiting-room blowout, is the talk of the hospital. (Side note: This is a pretty busy hospital. Don't these people have anything better to do than gossip about co-workers?) Anyway, she seeks solace with her AA buddy Richard (James Pickens Jr.), who talks her off the ledge, tells her she doesn't have to defend her past, and tells her to get to a meeting stat. Later, when Owen (Kevin McKidd) confronts Amelia about the outburst, she resists his help and stubbornly refuses to discuss the matter with him. 

I have to admit, Amelia's shame in these scenes kind of broke my heart. A+, Caterina Scorsone.

After the daughter apologizes for humiliating Amelia but notes that her parents' lives were at stake (she's got a point), Owen straight-up asks Derek if he should keep Amelia as the head of neuro. Derek is like, ¯\_()_/¯, so Owen decides to call an emergency board meeting. Realizing what he (might have) done, Derek gives Amelia a heads-up that she might be losing her job. She's understandably livid and yells at Derek for trying to take her job. He promises to try to fix it, but when Meredith tries to talk to him about it, he gives her the cold shoulder. But later, in the board meeting that Owen's called, Derek eats crow and says that, despite her history, Amelia has done well in recovery, and he admits that he was motivated by wanting his job back.

Quiz: How well do you know Grey's Anatomy?

Back in peds, while Arizona's calling Dr. Herman every five minutes, to no avail, Graham (Nicholas D'Agosto — whom, I'm sorry, but I can't think of as anyone but Ethan from Masters of Sex) is in crisis mode with the baby's mother. As Arizona is shuttling back and forth between the ORs, Alex (Justin Chambers) saves the baby's life, but the mother sadly dies. Then, just as Arizona — who, frankly, really needs to work on her poker face — is finally about to tell the baby's father that his wife didn't just face "complications" during surgery, but is in fact dead, Dr. Herman swoops in and informs him that Arizona saved his baby's life. Arizona is pissed about the day's events, but softens when she hears Dr. H puking her guts out in the bathroom afterwards.

Dr. Herman reveals that she's starting aggressive radiation, effective immediately, so that's why she went AWOL. But she's been watching Arizona from afar, Big Brother-style (creepy?), and agrees with all the decisions she made throughout the day. Dr. Herman says she'll impart more wisdom to Arizona more the next day — unless, of course, Arizona is planning to tell Owen about her condition. Arizona gives the most reluctant head-nod ever. (I really hope the season doesn't end with Arizona getting fired.)

After Jo gets through her first solo surgery easy-peasy, Bailey momentarily effs with her and pretends that the patient died — but just to teach Jo a lesson about having faith in herself. Now, I'm not a doctor, but that is a dick move, any way you slice it. I guess that "Nazi" nickname didn't come from nowhere.

Grey's Anatomy recap: Dr. Herman's secret is out

Then Jackson (Jesse Williams) and April (Sarah Drew) have baby talk outside. I'm sorry, but I'm so bored with their story line at this point that I'm paying more attention to Jackson's red sneakers than their dialogue. Next. (I immediately feel like a horrible person for typing this after I see the preview for next week's episode, which reveals that Japril's baby — the sex of which they're keeping a surprise, P.S. — may be in serious jeopardy. But as characters, they're still boring.)

Cut to Maggie and Meredith hanging out in bunk beds in one of the on-call rooms JUST LIKE REAL SISTERS OMG. Maggie finally admits to Meredith that she's pissed that she got stood up at a dinner party that she was basically forced to come to in the first place. She's lonely in Seattle, craving conversation, and "scared I'm going to get a cat." (Ha!) 

So Meredith invites Maggie to a good old-fashioned girls' night (plus Callie and Alex), and Maggie couldn't be happier. There's no dancing it out, but they all reminisce about the good times and pour one out for George (RIP). In the process, Maggie also learns about all their (gross?) sexual interconnectedness, and finds out that Callie is bi. Welcome to the family, Maggie! Everyone's having a grand time, except for Jo — who is off in the bedroom, probably browsing real estate listings for her and Alex in a gated community.

Then, Arizona crashes the party and says she was on her way home and "wasn't sure where to go." Is that a sliver of hope on the horizon, Calzona fans? Only time will tell.

Back at the hospital, the fire couple are on their way to recovery and the husband asks for Amelia, so he can thank her for saving his wife. (The daughter looks sheepish.) A happy ending, right?!

Not so fast.

Arriving at Derek's house after a long day, Amelia tells her brother she's moving out. In turn, he apologizes and confesses that he's angry and miserable all the time and doesn't know what to do. Amelia totally relates. Well. That is a far cry from the dinner-party-avoiding shower sex we saw last night.

What did you think, Grey's fans? Is there room for both Amelia and Derek at Grey Sloan? Will Derek tell Meredith his true feelings? And should Arizona be keeping Dr. Herman's secret? Sound off in the comments!

Grey's Anatomy airs Thursdays at 8/7c on ABC.