Grey's Anatomy

The staff tries to deal with physical and emotional trauma in the wake of the vengeful gunman's deadly rampage; Derek makes a decision to resign as chief.

Meredith finally tells Derek about her pregnancy and miscarriage; during a surgery, Cristina experiences PTSD.

Issues surface when Derek's estranged sister, Amelia, visits unexpectedly; Meredith and Derek continue to try to ease Cristina back into surgery.

Derek and Meredith visit the obstetrician and receive disturbing news; Lexie notices April and Meredith growing closer; Jackson tries to get ahead in the operating room.

As part of their training, Seattle Grace's residents are put in charge; the attending surgeons compete for a million dollar grant.

A documentary crew visits the hospital six months after the shooting to document the road to recovery for doctors and patients.

Owen puts the residents through a rigorous trauma certification drill; Cristina is left alone to monitor an ill lung transplant patient.

A team of doctors try to save the life of a political figure from the Middle East; Cristina decides to decorate her new place and throw a housewarming party.

Derek and the attendings go out to celebrate when he gets the grant he needs for his clinical trial; Meredith and Alex must fend for themselves during the night shift.

Concerned about Cristina, Derek tekes her on a fishing trip; Teddy directs her efforts and compassion toward a dying patient (Scott Foley) without the proper insurance.

A gunman open fires at a local college, sending mass casualties to the hospital; Arizona's return is not warmly welcomed.

Arizona tries to reconcile with Callie, who has big news to share; Teddy faces an important decision; the residents receive new interns; the Chief makes an announcement.

Meredith feels left out when Derek breaks ground on his clinical trial; Bailey's new idea does not go over well with the chief; Callie irritates her new obstetrician.

Meredith and Lexie's father returns to Seattle Grace with stomach pains and a new girlfriend; Alex butts heads with the new OB; Mark bribes Jackson for information on Lexie.

Meredith volunteers to run the ER for a night in hope of proving that she is chief-resident material; Bailey and Eli get into mischief; Adele comes to the hospital.

Meredith's fertility treatments start affecting her eyesight; Mark talks to Callie and Arizona about his role as a father.

Richard tries to get Adele into Derek and Meredith's Alzheimer's trial; Arizona and Mark try to plan a baby shower for Callie.

A cataclysmic event leaves the doctors shaken; Callie, on the verge of a life-changing moment, starts imagining about the hospital and her friends.

Everyone tries to help Callie and her baby recover; the death of a trial patient impacts Derek and Meredith in different ways.

Callie and Arizona's wedding is not coming together as they hoped it would; Meredith and Derek make a life-changing decision.

Work and personal pressures leave Meredith on edge; formal interviews for the chief resident position begin; Lucy and Alex's relationship is tested.

Meredith's dishonesty is revealed, leading to unexpected consequences for her and others; the new chief resident is chosen.