Back in his interrogation, the wind has gone from his sails as he quietly says that he got there in time and did the procedure. "I got off the phone," he says, as if he's just realized that his marriage might really be over because of it. Of course Izzie should understand completely if he has to go do his job and save someone's life and shouldn't be belligerent -- I think that's too much to ask. And no, he didn't tell her what was going on, but she knows he must be at work and has to go, which seems fairly self-explanatory for a surgeon. Ugh, she keeps giving me reasons to dislike her even when she's not actually around. Alex stayed with Cathy after that and reports that she was stable. He flips open his phone and just stares at the screen when out of the blue, he tells the panel that they started to lose her. He looks at her films and yells for a bunch of different things, giving the panel all of the medical details that amounted to her dying. Reed comes up to help and asks what happened, and Alex calls to Avery for help, all of the earlier malice gone from his voice. He then yells for a bunch of labs and has someone page Hunt.
April reports that she got the labs, and was shocked by what she saw. A tech runs up and asks if she is A.K., for April Kepner. She says no, that these are results for Alex Karev, but when she looks at the papers she runs straight to the ER. When she gets to the trauma room, it's pure chaos as everyone is working on Cathy since everything seems to be failing at the same time. Hunt is on the phone while he's in surgery working on Roy, trying to shout instructions, but finally he tells Cristina to scrub out and go see if she can help.
There was so much swelling, and no veins were available, so the docs had to do a central line. April tells the panel hopelessly that everything was failing at the same time. Cristina arrives as Cathy starts to code, and they try to shock her to get a heartbeat back. Things only go from horrifically bad to unimaginably worse when Reed notices that she's bleeding into the tube coming from her throat -- she's bleeding out on top of everything else. As Reed sits facing the Big Three, something clicks in her mind and she tells them, horrified, "I know what happened. I know why she died."
Back in the ER, blood is streaming from Cathy's nose and is pooling everywhere. The doctors are all yelling and trying to help, but the yelling is intermingled with the steady alarm of her heart not beating. Derek wades into the chaos and after doing some yelling himself finally manages to quiet everyone, telling them that it's over. He then tells someone to call it, but no one pipes up, even when he asks whose patient it is.