Seattle Grace is hit with mass casualties from a hotel fire - several burn victims, a guy with a fire ax sticking out of his chest and a firefighter who fell from a ladder and sustained multiple injuries.
But the central case is a woman named Kathy Becker, a young mom with a five-year-old son who, despite some pretty serious burns on her leg and less serious burns on her chest, seems to be on her way to recovery.
Seems being the operative word.
The problem is that there's no one doctor looking after her, and through the course of the night she's passed from pillar to post with no one overseeing her care. This leads to an interesting new way of storytelling.
April and Reed, two of the Mercy West residents, conduct the initial exam of mother and son, and everything seems all right. Then Mark and Lexie take over care of the second-degree burns on her leg.
Then in comes a 16-year-old burn victim who they have to attend to, though Lexie really wrestles with her emotions watching this kid suffer.
Then Reed gets pulled away to help Callie with the firefighter, who seems to be in pretty bad shape. April gets distracted by the insane sight of a patient coming in with a fire ax sticking out of his chest.
That situation is made worse when Charles, who gave blood that day, passes out and dislodges the ax, sending a spray of blood all over everything.
Cristina orders some morphine to help Mrs. Becker, who's been complaining of pain. She ends up suffering from a collapsed lung, which Lexie tries to fix with a chest tube.
Which she nearly screws up because she's distracted, and Avery helps her out by pounding Mrs. Becker's chest and relieving the pressure.
The patient is stable, and for a minute we're distracted by Arizona yelling at Lexie to pull it together and Alex frantically trying to reach Izzie, who's been gone for a week, while having to stitch up the forehead cut of Charles.
Mrs. Becker's having awful trouble breathing, and Alex has to perform an emergency cricothyrotomy to be able to open her airway. Then she starts to slide.
Her carbon monoxide levels and labs are all over the place before she begins bleeding out. It's over, even though at this point pretty much every doctor is working on her - Cristina, Alex, Charles, Avery, Reed, and April.
Then it hits Reed that in her initial examination of Mrs. Becker, April was distracted and skipped checking her airway. Had she done so, she would have found soot and would have intubated the patient right away.
One simple mistake led to a dramatic, chaotic turn of events and a horrible end. April gets fired.
All of the residents from both hospitals were running around competitive and terrified, most of her Mercy West colleagues aren't exactly sympathetic.
Cristina pulls "that's one of us in there" moment and admonishes everyone, saying that it could have been any of them.
In the end, though, Derek puts the blame for the mistake on whom it belongs: the Chief. Derek says he found the trauma room in chaos, with too many doctors who don't know each other and don't trust each other.