Derek's mother, Carolyn, makes a surprise visit to Seattle and meets Meredith for the first time, as Mark tries to conceal his relationship with Lexie from her as well; meanwhile, death row inmate William wishes to donate his organs to Bailey and Arizona's patient, as Owen and Cristina try to go on their first date.

As Derek begins his role as interim chief, he faces a potential lawsuit when Bailey and Meredith's patient awakens from anesthesia mid-surgery. Meanwhile, Teddy refuses to place Cristina on her service, as Arizona tests Alex out in Pediatrics, and Mark refuses to speak to a heartbroken Lexie.

When Teddy's patient seeks to end treatment and her life, she turns to Hunt for help. The situation triggers Hunt's memories of his life at war and his past relationship with Teddy. Meanwhile, Callie and Arizona have a difference in opinion on what their future holds, and Richard tries to adjust to his role as a surgeon.

A team of doctors tries to save the life of a political figure from the Middle East; Cristina decides to decorate her new place and throw a housewarming party; Alex shows up late to his first day of rounds with the new pediatrics attending.

As Meredith puts Zola to bed and falls asleep, she begins to wonder -- what if her mother had never had Alzheimer's and she'd had loving, supportive parents? The reverberations of a happy Meredith Grey change the world of Seattle Grace as we know it. What if she had never met Derek in that bar and he had never separated from Addison? What if Callie and Owen had become a couple long before she met Arizona? And what if Bailey never evolved from the meek intern she once was?

As word of Seattle Grace's financial trouble spreads, Catherine encourages Jackson to move to Boston, and the interns fear they might lose their jobs. Meanwhile, the doctors meet with a potential investor in a last-ditch effort to save the hospital, and Alex impresses Jo while caring for a patient.

When an unexpected malpractice suit turns Callie's world upside down, her supportive father arrives and shares an interesting secret with her. Meanwhile, through flashbacks, we learn some surprising details about Callie and Arizona's marriage.

Maggie gets upset when Meredith dodges her questions about DC; Bailey and Ben become concerned about Ben’s brother after he is admitted to the hospital, and Dr. Herman starts to warm up to Arizona. Meanwhile, Richard feels manipulated by Catherine.

Grey Sloan Memorial not only welcomes a new transfer resident, but also a patient who's the topic of converstation after accidentally sending his sex tape to his entire congregation. Meanwhile, Richard wrestles with how to progress his relationship with Maggie when an old friend visits the hospital, and April brings in a case of a young boy from the Middle-East.

After a missing child forces the hospital into lockdown, Ben decides to operate on a pregnant mother without the proper surgical equipment. Miranda, as Chief, is faced with the repercussions of the event and whether or not Ben's impulsive actions were justified.

The arrival of a new consultant puts all of the doctors on edge, especially once she starts stepping on toes in the OR. Amelia and Owen bring their personal problems into the hospital, while April explores some uncharted territory.

The residents are excited for Eliza’s next phase of teaching, but they spend the day caught between the warring attendings. Meanwhile, April has a challenging first day in her new role at the hospital.

April is in charge of the new Grey Sloan Surgical Innovation Contest, and the doctors are eager to start their projects. Meanwhile, Catherine’s old friend has a shocking idea for Catherine and Jackson; and Meredith treats a returning patient who inspires her project.

An agent from ICE shows up at Grey Sloan in search of an employee who may be working in the U.S. under DACA. Alex’s patient Kimmie wants to leave the hospital to enjoy her final days, but Alex feels differently. Meanwhile, Arizona treats Matthew Taylor’s baby and April wants to do whatever she can to help.

Meredith breaks a hospital record; the doctors are sent scrambling in the wake of a massive overdose within the community; Jackson wants to take Maggie camping; Levi and Nico's relationship continues to develop.