So, did it work?

When we left off with Grey's Anatomy last week, Amelia (Caterina Scorsone) was about to tackle the biggest case of her life: removing a potentially fatal tumor from Dr. Hermann's (Geena Davis) brain.

"A surgeon must always be prepared to lose," we hear Amelia say in a foreboding voiceover at the start of the hour, before she brushes off a concerned Owen (Kevin McKidd) in order to give herself her own pep talks in the bathroom mirror, briefly break down, and then assume the stance of a superhero in the scrub room.

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With a full gallery of onlookers staring at her and Stephanie (Jerrika Hinton) by her side narrating, Amelia takes a deep breath, starts the clock and begins the operation. Up in the box, Maggie (Kelly McCreary), speaking for all of us viewers at home, casually wonders where the appeal is in watching what could potentially be the worst day of someone's life.

But it's also a learning process, and thanks to a cool green dye, we and the observing doctors get to see just how massive Dr. Herman's tumor is. Welcome to Grey's Anatomy: The Secret of the Ooze!!

Grey's AnatomyGrey's Anatomy

Meanwhile, in another OR, Bailey (Chandra Wilson) is horrified to discover that Arizona (Jessica Capshaw) will be standing in for Dr. Herman on the surgery for her pregnant patient Glenda. As they argue about whether to deliver Glenda's baby, Bailey (clearly still uncertain about Arizona's capabilities) pages Alex (Justin Chambers) to assist. Eventually, with Dr. Herman's voice in her ear, Arizona stands up to Bailey and goes with her gut on the fetal surgery.

Back in the observation deck, Webber (James Pickens Jr.) notices that Amelia is tense, and she has good reason to be - she's essentially hit a dead end with the tumor. While Amelia stalls, April (Sarah Drew) returns to the hospital for the first time since losing her baby to offer moral support for Dr. Herman, who saw her through her own tragedy. Webber enters the OR and offers to pitch in on the surgery, and Amelia eats a massive dose of humble pie and begs him to call her brother Derek, admitting with tears in her eyes: "I am in over my head. I made a horrible mistake."

But Webber won't do it. He tells Amelia to stop thinking Derek's better than her and take charge of the surgery. And Amelia takes his advice, crossing the "point of no return" eight hours into the surgery and showing no signs of slowing down.

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As the hours tick by, Amelia starts to breathe a sigh of relief - and I, for one, reflect on the fact that I can't imagine doing anything for 13 hours, let alone perform brain surgery. Apparently that's also a problem for Stephanie, who falls asleep on her feet, prompting Meredith (Ellen Pompeo) to scrub in. Amelia hits a nerve-wracking setback when, upon realizing that she can't operate quickly enough with protective gloves on, she removes them, exposing herself to direct radiation and causing Owen to flip the eff out up in the box.

Elsewhere, Arizona (after saving Glenda's baby's life and earning some praise from Bailey) takes a rest and quietly reflects on how far she and Herman have come in the past few months. Callie (Sara Ramirez) interrupts her reverie to congratulate her ex-wife on her solo surgery and invite her in to watch the final hours of Herman's surgery. But a worried Arizona says she can't do that and starts crying, leaning on Callie and taking her hand for comfort.

At 17 hours and counting, Amelia is visibly exhausted as she finishes up on Dr. Herman. Meredith tries to convince her sister-in-law to let someone else handle the final steps. Enter Stephanie, who has woken up on a gurney minutes before. After passing the torch scalpel off, Amelia goes into the hallway and collapses in relief. (Am I the only one who's still really worried that something is going to go wrong at the last minute?)

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What looks like days and maybe even weeks go by - enough time for Glenda to fully recover and leave the hospital - and Dr. Herman doesn't wake up. Amelia binge-watches tapes of the surgery on a loop to try and figure out what went wrong. In the end, it's Stephanie who notices on an X-ray that Dr. Herman may have had a stroke. The decision about whether to take Dr. H off life support falls to Arizona, who turns to Callie for support since she had gone through the same thing with Mark.

And then - miracle of miracles! - Dr. Herman wakes up (cracking jokes, no less!). But, oh. The bad news is that she's completely blind. However, it seems that Herman has adopted a new outlook on life, telling Arizona that she's grateful to be alive. Stephanie's crushed, but Amelia is vindicated, noting that they defeated the tumor that stole Dr. Herman's sight.

What do you think, Grey's Anatomy fans? Were you surprised by the outcome of Herman's surgery? Do you think Callie and Arizona could be heading towards a reconciliation? And how much caffeine would you need to make it through an 18-hour surgery? Sound off in the comments!

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

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