Thriller

"Every Halloween we make a choice about what kind of costume we're going to wear. Something sexy, maybe we'll be someone scary, or you could be a superhero, which is what I'm trying to be this year. Halloween is not for the faint of heart. There's a surprise around every corner. Some of the surprises are good, and some of the surprises are bad. What's important is that you can't let the fear of the surprise stop you from getting dressed up and wandering to a stranger's house to ask the question. So, what'll it be? Trick... or treat?"

- Meredith Grey

 is the seventh episode of the tenth season and the 203rd overall episode of Grey's Anatomy.

Short Summary
It's Halloween and the doctors of Grey Sloan Memorial are hit with a barrage of spooky patients, which affects their own plans and puts one doctor’s well-being in jeopardy. Meanwhile, Derek collaborates with Ben on a new surgical technique and Richard angers Bailey when he asks a second year resident to perform his next surgery, on a special Halloween episode.

Full Summary
Leah wakes up next to Arizona in the hotel room. She gets ready to leave, but Arizona asks if she wants breakfast. Leah says she knows she's not supposed to sleep over and apologizes, but Arizona says it's okay. Leah thinks it's not, as she's all about easy, and she leaves to find a costume for Jo's party tonight. Arizona then remembers it's Halloween. She tries to wish Leah a Happy Halloween, but Leah leaves.

An extremely busy Meredith meets Derek in the hallways of the hospital. She hands him over the wings of Zola's butterfly costume and asks him to take care of the rip of the wings. She now has to order a 3D printer for her research, for which the grant was approved. He tells her a little about his brain mapping project and after asking if the party tonight is still on, he leaves her. Meredith asks Alex if he got the house ready for the party, and he says he did. However, he only got the cake and forgot about the rest. Cristina overheard them talking and asks them if they're having a party. Meredith says they'll trick-or-treat from Alex's house after the Halloween party with families from the daycare, because they don't have neighbors around their own place to trick-or-treat. Cristina didn't know about this, and Meredith says she should come. Cristina doesn't seem enthusiastic about the idea, and Meredith says she probably doesn't want to be around kids hopped up on sugar. "Right, cause I hate children," Cristina says, after which she says that she does love Meredith's kids. Meredith then apologizes for not having invited her, and then invites her to come and have a drink.

Jackson and Stephanie, who's wearing special glasses, enter the hall, where Jo and Leah ask her if she doesn't have any side effects from her eye surgery, as Leah's uncle still has pain from the same surgery he had 3 years ago. Jackson makes a comment about Stephanie coming back to work too early while she should stay at home for 2 days. "I'm a second year resident, 16 hours of recovery is already more than I can afford," Stephanie says.

She and Jo enter the small room with computers, where Jo informs her that Alex still hasn't talked to her, making her think their relationship is over. Stephanie doesn't believe this, and says it's time to go round on Webber. As she wants to walk outside, she walks into the wall. "Are you sure you don't want to go home?" Jackson asks.

At a nurses station, Callie asks April and Owen if they have Halloween plans. April says she'll go to Matthew's thing as a Velveteen bunny, and Callie comments that the costume still needs work. She asks Owen about him and Emma, and Owen says they're no longer a thing, as Emma thought he wasn't ready yet because he never mentioned being married before. Emma told him to call her when she's ready, and as Callie and April start discussing whether or not he's ready, Owen walks away. They then agree he's not ready. April leaves, when Arizona comes over to ask Callie what time they want to meet for Sofia's costume, which she has in her car. It turns out they both have different costumes for Sofia, a princess costume and an astronaut costume, as she told her mothers different things she wanted to dress up as. Arizona proposes to let Sofia decide between the costumes, but Callie says Arizona can take Sofia.

Bailey enters Richard's room, where Stephanie tells her that Richard will allow one of the interns to perform his surgery. "Not you, no offence, but I heard you walked into a wall this morning," Richard says. Bailey asks why she can't do the surgery, and thinks the interns are not ready, contrary to Richard. He asks them how to explain how they'd do the surgery, and suddenly Ben Warren answers his questions from the doorway. Bailey hugs him, and he tells her he came early because he didn't want to miss trick-or-treat. Ben asks which intern he's going to pick, and Richard tells Bailey to observe them in the ER so she can tell him which one deserves it. She starts to object, but Richard has made his decision, so Ben pulls her out of the room.

Main Cast

 * Ellen Pompeo as Dr. Meredith Grey
 * Sandra Oh as Dr. Cristina Yang
 * Justin Chambers as Dr. Alex Karev
 * Chandra Wilson as Dr. Miranda Bailey
 * James Pickens, Jr. as Dr. Richard Webber
 * Sara Ramírez as Dr. Callie Torres
 * Kevin McKidd as Dr. Owen Hunt
 * Jessica Capshaw as Dr. Arizona Robbins
 * Sarah Drew as Dr. April Kepner
 * Jesse Williams as Dr. Jackson Avery
 * Camilla Luddington as Dr. Jo Wilson
 * Gaius Charles as Dr. Shane Ross
 * Jerrika Hinton as Dr. Stephanie Edwards
 * Tessa Ferrer as Dr. Leah Murphy
 * Patrick Dempsey as Dr. Derek Shepherd

Guest Stars

 * Jason George as Dr. Ben Warren
 * Mary Pat Gleason as Marge Walker
 * Eric Ladin as Victor Brown
 * Lorna Raver as Ghost Lady
 * A. Russell Andrews as Mr. Davis

Co-Starring

 * Robert John Brewer as Philip Walker
 * Laya DeLeon Hayes as Taryn Davis
 * Marcanthonee Jon Reis as Tuck
 * Teresa Huang as Nurse Ruth
 * Kate Mines as Nurse Gloria
 * Grace Rowe as Paramedic Grace
 * Louis Carazo as Bartender
 * Eddie Navarro as Zombie
 * J. Omar Castro as Paramedic #2
 * Melanie Jean as OR Nurse #2

Patient

 * Diagnosis
 * Doctors:
 * Treatment:

Notes and Trivia

 * This episode's title originated from the song , originally sung by Michael Jackson.
 * This episode scored 8.94 million viewers.
 * Many of the characters were dressed up for Halloween:
 * Cristina Yang put on a hat at Joe's bar to look a little dressed up like a witch.
 * April Kepner told Callie that she'd dress up as a Velveteen bunny for Matthew's thing.
 * Jo Wilson dressed up as Tinkerbell.
 * Shane Ross wore a ninja costume.
 * Stephanie Edwards was dressed as a clown.
 * Leah Murphy was dressed as a cowgirl.
 * Ben Warren impersonated a Zombie.
 * Taryn Davis wore a witch costume.
 * Little Tuck was dressed as a mad scientist.
 * Zola Grey Shepherd was dressed as a butterfly.
 * Derek Bailey Shepherd wore a pumpkin outfit.
 * Sofia Robbin Sloan Torres was dressed as a space princess, combining the princess and astronaut costumes her mothers made for her.
 * Several trick-or-treaters were shown, and shown costumes were zombies, witches, princesses, Cleopatra and a ladybug.
 * Marguerite Moreau makes an uncredited voice-only appearance as Dr. Emma Marling when Owen calls her and her dialogue can be heard by the audience.
 * Goof: In Map of You, the interns have just passed their intern exam and are 2nd-year residents, which means it's early July. In this episode, it's Halloween (and so it takes place at the end of October), which means four months have passed instead of the said three.
 * Goof: In Map of You, Derek decided to step back from surgery to allow his wife, now a 2nd-year attending, to take on her new workload. In this episode, he says to Ben that it's only been a week, which doesn't account for the three-to-four-month time jump between the two episodes.

Quotes

 * Cristina: You're having a party at the house?
 * Meredith: Yeah, Alex is letting us use the house to trick or treat from because we have no neighbors around were we are, so I invited a bunch of families from the daycare. He didn't tell you?
 * (Cristina shakes her head.)
 * Meredith: You should come!
 * Cristina: It's fine.
 * Meredith:' Right, well, you don't wanna be around a bunch of kids hopped up on sugar anyway, right?
 * Cristina: Right, cause I hate children...


 * April: Matthew has this thing, I'm going as a bunny.
 * Callie: Playboy?
 * April: Velveteen.
 * Callie: Needs some work.