The staff deal with a boy, who literally has become a tree; a patient who vocalizes all his thoughts aloud, no matter how rude; and a lung cancer patient, who ends up having sex with Alex in Joe's restrooms. Meanwhile, the Nazi is back with a vengeance from recent events, Burke's mother catches Cristina offering a new hospital service, Callie covers for Meredith, Izzie starts baking out of grief and Derek and Addison find their marriage is over.

Addison and Alex treat an abandoned baby, George and Derek are sealed off from the rest of the hospital (possibly with plague), Izzie mourns for Denny, Meredith tries to choose between Derek and Finn, Callie and Cristina try to help Izzie, Bailey helps a distressed patient and many of the doctors have flashbacks from their past.

Season 2 Finale!!

Richard is determined to discover the guilty party, and punishes the interns by making them arrange a prom for his niece. Meanwhile, Callie presses George about his feelings, and Derek and Meredith have to make a decision about Doc.

Cristina gets assigned to a trauma all by herself. Izzie and George wait for Burke to arrive and help Denny get the heart, but they do not realize that Burke has been shot and has to undergo surgery. Meanwhile, the Chief's niece Camille has been admitted to the hospital.

The victims of a workplace shooting are admitted. Izzie puts her job on the line to ensure Denny gets a new heart, Callie makes an effort with Meredith, and Addison is suspicious of Derek.

TW: gun violence

Anger is in the air, as Derek is angry at Meredith for seeing McVet, Burke is angry at Cristina for falling asleep before he finished, Alex is still angry at She-Shepherd pulling him off surgery, Callie is angry at George for not defending her and the patients of a car crash are angry at the doctor responsible for the crash.

Burke has to operate on his idol, Eugene Foote, causing him to conflict his views between potentially killing his idol or risk letting Foote find somebody else. Bailey continues to be mommy-tracked, while Alex has to deal with a strict Catholic family where the mother wants a tubal ligation without her husband knowing. Meanwhile, a divorce attorney is reading Derek like a book about his marriage as Izzie grills George about his living arrangements.

In light of recent events, Bailey is being mommy-tracked, so she becomes Derek's intern to get some OR time. George discovers many secrets during the day, not least that Meredith has a sister, one of Addison's patients, and Callie is living in the hospital. Meredith begins knitting with Izzie, while the Chief and Cristina battle it out during a skills class.

Surgical fatalities occur in threes and sevens, at least that's the rumor on the surgical floor. With four fatalities in the morning alone, superstition rules the roost at Seattle Grace, so Addison jujus Meredith for good luck. Burke has George retrieve a scrub cap Cristina is holding hostage, Meredith and Bailey try to convince a friendly stalker to operate and Cristina is annoyed endlessly by her OCD patient while Richard's past arrives in Seattle Grace.

Cristina is left holding Bailey's baby when she is unable to get anyone else to get anyone to watch him, while Meredith confides in Derek, while Derek performs a risky surgery for a supposed inoperable aneurysm. A patient's husband gives Addison attention and George and Callie give each other their full attention while treating a stubborn hockey player.