<P> The episode begins in medias res, depicting events following a whodunit style, exposing them from alternating points of view in a fast - paced way . Katherine Heigl (Dr. Izzie Stevens) was absent from the episode, due to her hiatus to film the 2010 blockbuster Life as We Know It . Upon its initial airing, the episode was viewed by 15.40 million people, garnered a 5.6 / 4 Nielsen rating / share in the 18--49 demographic, and ranked first for the night in terms of viewership and ratings . </P> <P> After victims burned in a hotel fire are brought to the hospital, Seattle Grace and Mercy West residents compete to get the best cases . Unexpectedly, a woman (Cathy Becker, played by Erinn Hayes) about to be discharged dies after a medical negligence mistake committed by one of the many surgeons who treated her . Chief Webber then starts a witch hunt to trace back the culprit and identify the cause of death . Each doctor gives his point of view of the chaotic scene that happened in the ER that day: Owen, Cristina, Bailey, Alex, Callie, Lexie, Charles, Jackson, April and Reed . The case of the patient then starts to be reconstructed . Her deep second degree burning, her chest pain, her pneumothorax and the cricothyrotomy Alex had to perform on her are exposed, as well as several other parallel storylines and medical cases linked to the fire . </P> <P> Reed ultimately realizes that the mistake was committed by April, who forgot to check the patient's airways, already swelled by the smoke, after being distracted by a patient with an axe stuck in his chest . Richard then fires her . The residents are shown having various reactions, as some complain about the absurdity of April's mistake, while Cristina shows empathy for her former enemy . Derek then criticizes Richard, telling him he was initially responsible for the situation by setting chaos in the ER with the merger . </P> <P> A subplotline of the episode includes Alex desperately seeking Izzie and calling her frequently to convince her to come back, even threatening to file a missing person report . </P>

Grey's anatomy who killed the burn victim