It's all hands on deck at Grey Sloan when a group of medical students is injured by a floor collapsing at their white coat party. Jo and Link are forced to talk about the future, while Jules confronts Winston about his attitude.

Dr. Arizona Robbins returns to Grey Sloan for a particularly complicated case. The interns are interrogated about their past mistakes, while Teddy is eager to return to work after her health scare.

The aftermath of the convenience store shooting brings chaos to Grey Sloan. Ben hits a wall with his new emergency preparedness plan. Romantic tensions surface for Owen, while Amelia and Winston disagree over the surgical plan for a young patient.

Derek is still operating when he finds out about Meredith's current situation. Meredith is freaking out about her situation. Webber and Bailey are dealing with medical health issues. Cristina and Izzie have their own issues to deal with because of Meredith's situation. Addison freaks out when George tries to find a solution to Bailey's impromtu postponement. Overall, Seattle Grace Hospital is still under code black and the situation is getting worse.

Seattle Grace Hospital is hit with a crisis like no other in its' history.

When a trauma patient arrives at Grey Sloan, it forces Jo to confront her past. Meanwhile, Bailey and Ben have to talk to Tuck about dating.

On the heels of life-changing news, a thunderstorm hits Grey Sloan. The attending surgeons and interns work together to save an injured reporter and family affected by the storm. Meanwhile, a beloved author undergoes a risky surgery, and complications from the storm arise.

Meredith and Nick return to Grey Sloan to treat a liver transplant patient. Meanwhile, Bailey hosts an intern retreat at her home, and Winston and Ben aid an unexpected crash victim.

Following a difficult case, the team faces the complexities of medical ethics. Meanwhile, Bailey continues to navigate her working relationship with Ben, while a group of college students on a scavenger hunt causes chaos around the hospital.

Train Wreck victims come to Seattle Grace and all staff gets called in. Everyone deals with really weird cases. Except Addison and Izzie. They work with a woman who is pregnant.

An explosive case arrives at the O.R. that might endanger all the lives of the people working there, which leads Dr. Burke to declare a "Code Black" for the hospital. Bailey worries where her husband is as she is in labor. Also Izzie and Alex may be creating some heat.

Meredith is still underwater, but nobody seems to notice. Her worsening condition makes her rescuing an urgent matter. Derek finds her coat on a man she had helped, and starts looking for her and, much to his shock, the little girl Meredith took care of suggests that she is in the water. Derek saves her, but she is almost dead, due to hypothermia. Izzie has to perform brain surgery on a man stuck between cars, as he begins to experience seizures. She drills holes into his head, perforates his skull and ultimately saves his life before he is rescued and transferred to Seattle Grace Hospital. George lies to the woman whose son he had been looking for, in order to get to surgery, but still doesn't have any luck in locating him. Alex finds no hope in searching for the pregnant Jane Doe's family as she undergoes surgery. The interns find out about Meredith's situation and express their hopelessness. She wakes up in what appears to be limbo and meets her deceased acquaintances.

In the second part of the two hour season finale, George delivers stunning news to Bailey, sending shockwaves throughout the hospital, and Izzie's friends anxiously await her recovery from surgery. Meanwhile Bailey is surprisingly displeased after being accepted into the pediatric fellowship program, and the victim of a near-fatal traffic accident brings the talents of Seattle Grace's doctors together. This is the second hour of a 2-hour season finale.

Meredith and Amelia work to secure funds for their research while Amelia finds herself at odds with a new attending. Levi runs into someone from his past, and Owen gives Winston advice. Lucas ditches Mika, forcing her to treat a patient alone.

Due to a blood shortage, Grey Sloan Memorial is setting up a voluntary donation center. Meanwhile, Nick asks Meredith for help with his patient and Winston is hung up on his relationship with his brother.

Simone and Lucas work to balance their relationship while competing to assist on an awake kidney transplant. Teddy offers Amelia a new opportunity, and Ben's interview doesn't go as planned. Meredith's secret causes tension with Richard.

Mika struggles with a life-altering personal matter. Meanwhile, Bailey and Ben navigate their personal and professional roles, while Levi finds a connection in an unlikely place. Jo and Link get surprising news.

Teddy and Owen plan a date night that gets derailed in more ways than one, while Jo struggles to do it all at home. Mika adds more to her plate to make up for taking time off to be with her sister, and Levi is faced with a monumental decision.

The doctors at Grey Sloan must put aside their emotions under intense circumstances. Levi asks James a shocking question that could impact their future.

Meredith and Amelia prepare a funding proposal for their Alzheimer’s research. Meanwhile, Teddy and Owen hit a breaking point in their marriage, while Jules has an awkward encounter with Dr. Beltran.

Amelia and Simone attempt to perform a high-stakes and groundbreaking brain surgery. Teddy and Bailey attend a medical conference and run into Dr. Cass Beckman. Meanwhile, Jo struggles with her irritation toward a younger OB-GYN.

Amelia undertakes a high-risk brain surgery on a young patient, while Winston and Jules disagree over how to handle their trauma patient's family. Jo and Link struggle with wedding planning.

Bailey grows desperate as a patient's condition becomes more and more dire. Everyone in the hospital is stepping up to try to find the boy a new organ donor, including Meredith, who considers a death row patient's wish to die before execution. Meanwhile, an injury leaves Mark in a compromising position in the OR and Cristina awkwardly avoids Owen.

As Cristina tries to recover, she proves to be a very difficult patient, and a visit from her mother doesn't improve her demeanor any. And Meredith's mother, Dr. Ellis Grey, has the hospital staff running in circles.

George and Derek work together, Denny still doesn't have a heart, and Meredith gets paired with Callie. A 12-week pregnant girl dies in the O.R. and her parents try to keep the baby alive. This causes tension between Derek and Addison. One doctor's overreaction unites two bickering patients. Finn is still treating Doc for medical problems.