Wildfires threaten the Seattle region, leading to a flood of patients and emergency procedures. The doctors juggle overcapacity in the ER, complex surgeries and personal stress. Meanwhile, Meredith makes a rash decision that can't be undone.

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.

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.

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.

An unexpectedly complex case brings back painful memories for Simone. Jules and Blue make a high-stakes bet on who can finish their procedure log first. Richard suspects Winston is avoiding him.

Just as Amelia comes to a realization, Teddy encourages her and Meredith to speed up their Alzheimer's research over fear of Catherine finding out. Mika finds herself caught in the middle of Link and Jo; meanwhile, Lucas receives bad news.

Mika and Teddy receive a patient from a nearby penitentiary. Catherine pushes back on Link and Monica's treatment plan for a VIP. Bailey tries to integrate wellness into the residency program.

Meredith rethinks her plans. The interns are on thin ice following a patient's death. Simone and Lucas are immediately tested in an emergency. Richard confides in Bailey. Teddy's fate is revealed.

Bailey tells the interns they must complete dozens of basic procedures before being allowed back in surgery; things are awkward between Simone and Lucas; Amelia comes up with a solution to a complicated surgery.

Owen and Teddy have the day off but encounter an injured civilian. Monica enlists Amelia's help with an operation on a young patient. The interns complete their procedure logs, allowing them back into the OR.