While Izzie narrates, Meredith and Derek are at the church where they will be getting married at the end of the day. They are excited.

At Seattle Grace, Callie wakes up and complains to Cristina that she has to pick up extra shifts in the ER since she has no money.

Also, she apparently had a romantic date with Arizona last night at a fancy restaurant she can no longer afford, then bailed after to work.

Cristina also slept at the hospital and is cranky.

Izzie is super-excited to be going to the wedding today. She tells Bailey she feels fine and that she must go to the wedding. Alex is concerned that her blood pressure isn't where it should be.

Once they both leave the room, Izzie notices that her hair is starting to fall out. Then, Denny shows up again, causing Izzie much distress.

She knows that there must be another tumor in her brain.

Alex and George are assigned to the pit, but Callie tells them they can relax because there's nothing to do. It's a slow day. Worst jinx ever.

Sure enough, a phone call comes in from an ambulance carrying bloody trauma victims. The patients are a group of college students who were on their way to their graduation but were in a terrible car accident.

The surgeons scramble to deal with the carnage.

Hunt is on the bridge with Cristina. He tells her that it was the blades of the ceiling fan above her bed that triggered his PTSD episode, as it reminded him subconsciously of the helicopter blades in Iraq.

He wants to hold her hand, but she abruptly leaves.

Hunt joins the rest of the team in the ER. Alex's treats the valedictorian of the class, named Becca. All she ever did was study, and her life was supposed to begin today ... after she graduated from college.

Cristina's patient was driving, and he asks about his girlfriend. He says she was sitting in the backseat, and when he turned around to tell her something, she was gone.

Izzie pages Derek and tells him about the new visions of Denny. Derek knows what that means and orders another MRI.

Richard pages Meredith about a wedding present. He says it's Derek's present to her, but he has to oversee it. Meredith doesn't want any gifts, but when Richard says that the present is actually an inflamed colon, and assigns her to her first solo surgery, she smiles and agrees. Scrub in!

George's first trauma patient dies, and Hunt convinces him that he can't save everyone in this line of work, and you have to move on to save the people you can, and go where you are needed.

Arizona interrupts Callie's hectic day in the pit, asking what's up. They had gone to a great four-star restaurant, and it was supposed to be so romantic, but all Callie did was order a salad and bail.

Callie doesn't really respond because she has so much going on in the ER. She runs off to yell at some paramedics instead .

Bailey tries to convince Izzie to stay positive as she gets her ready for the MRI, but Izzie is convinced it's a tumor.

Denny is standing right behind Bailey and says hi.

Becca, Alex's patient, continues spilling their guts. She tells him about how she should have slept with David, George's patient who just died, when she had the chance, but now he's dead and he can't.

Cristina's patient also starts talking. He has to be separated from his girlfriend for some reason, and he knew that their relationship wouldn't last, even though he loves her.

George is working on another patient who is bleeding so much that there's no way to save him. After he dies, George is so disgruntled that he asks Hunt to pull him from the pit. Hunt will not.

Another patient is brought in, practically cut in half, her guts literally are spilling out. She's D.O.A. She's the girlfriend of Cristina's patient, who sees her. When he realizes his girlfriend is dead, he starts coding.

Richard scrubs in on Meredith's surgery, which annoys her a bit since it's supposed to be a solo surgery. He gets very parental, commending her on things and being subtly critical here and there as well.

Mark crashes the surgery as well to tell Meredith that she better not leave Derek because he doesn't want to be Derek's best man a third time.

Arizona wonders why Callie was so tired after their date, yet she has all this energy to be working the ER. Callie says she rallied because she ... well, she just loves the pit.

Arizona knows she is lying and wants to know what's up. Arizona gets angry and wants to know if their relationship was just a fling.

Izzie, Bailey and Derek can't see anything in Izzie's brain scans, but Izzie knows that she wouldn't be seeing Denny unless there were something.

Derek gets the idea to hook her brain up to a monitoring device so that if she gets another hallucination, they'll be able to pinpoint where it is.

Alex's patient Becca is still freaking out, so he suggests that she give him her valedictory speech since she worked so hard on it. As she does, we see all of her friends being zipped into body bags in a poignant montage.

Denny finally appears to Izzie, and Derek finds where hallucinatory neurons are firing in her brain. The part of the brain is the other temporal lobe, and the tumor was too small to pick up on an MRI.

Bailey wants to know how they can take it out, but Derek says that there's nothing they can do. Ah, but there is something: Bailey has an idea.

Arizona interrupts Callie while she is taking a nap and yells some more. But Callie finally confesses that her behavior was due to the fact that she is broke and can't afford fancy four-star restaurants anymore.

Her father cleaned out her bank account and disowned her. Arizona says that she doesn't care, and they can stay in and eat pizza.

After Meredith's surgery, Richard tells her Ellis would have been very proud to watch her do her first solo surgery.

George is down on himself. All the patients he treated died today, and the only one who survived was the one he didn't treat. Hunt tries to pump up George's deflated ego, saying that because George treated the other five, that allowed Hunt to go and save the sixth.

He says that trauma is a team sport and he's a hero too.

Lexie cries as she treats the sixth patient who survived.

Meredith tells Derek excitedly about her first solo surgery, and that she is having a great wedding day. Derek asks Meredith if she wants to make the day even better.

Meredith finds Alex outside. He just heard that Izzie has another tumor, and he's afraid that she might die on him. Meredith shares Bailey's idea.

That idea, of course, is that Izzie and Alex should get married instead of Derek and Meredith. After all, this is Izzie's dream wedding.

At first, Izzie thinks Meredith is just having pre-wedding jitters, but then Alex, dressed in a tux, pops into her room.

At the church, Izzie is all dolled up. Meredith asks who's going to be the maid of honor, her or Cristina, and Izzie immediately says Cristina.

Izzie reassures Cristina that she is very maid-of-honorable since she tried to save her life. Alex in turn wants Meredith to be his best man.

The wedding begins and Izzie walks down the aisle. But she's too weak to walk down by herself, so George leaps up and helps her down the aisle.

It's time for the vows, and Izzie is worried since she didn't prepare any. But Alex jumps in and recites a version of Becca's valedictory speech he made her recite, about this being the beginning of his life, the day he becomes accountable to someone other than himself.

It's awesome.

As Izzie and Alex kiss, everyone gets teary-eyed.

Back at the hospital, Alex tucks Izzie into bed again. He takes the flowers out of her hair and a good chunk of hair comes out with it.

He assures her that she doesn't need her hair and that she would still look great without it. She should even shave it all off. She cries.

After the wedding, Callie and Arizona get naked and eat pizza, Cristina takes down her ceiling fan, and Meredith and Derek lie by the fire.

In bed, Izzie again has a scarf on her head. She has been talking to Denny. She tells him to go now because she wants to be alone with her husband.

Alex walks in and asks why she's wearing the scarf. She takes it off to reveal she is bald. My wife is so hot," Alex says. Roll credits.

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