When Diane's health deteriorates, the doctors brainstorm to come up with a way to help her. Her cancer has spread to her stomach and Meredith decides that she can't operate.
Meredith tells Maggie and Diane that surgery would be too high-risk. Maggie disagrees with Meredith. Diane ends up firing Meredith as her doctor to make Maggie happy.
Jackson, Bailey, and Richard find a clinical trial to get Diane into. They don't agree with the choice but Maggie wants to do it anyway. It makes Diane feel worse.
Diane decides to have a family dinner to teach Maggie her recipes and thank the doctors. She invites some of the others to Meredith's.
When Diane's esophagus begins to bleed, they realize the treatments are doing her no good. Maggie still wants to keep going but Diane can't anymore.
Maggie and Meredith butt heads about how to help, but Meredith continues to support Maggie. She tells her how to deal with losing a parent, and tells her that no one is ever ready.
Maggie spends time with Diane. Diane gives her life advice and tells her to really live and love. Diane dies while Maggie is painting her nails.
Nathan is there to console Maggie and be her friend through the ordeal leading up to her mother's death.
Nathan tries to be there for Meredith too. Meredith finally tells Nathan that the timing isn't the best because Maggie needs her right now, so they call their thing off.
Richard and Bailey continue to bicker while treating Maggie's mother, but eventually come closer to making amends by the end, after Diane dies.
Richard arranges for Maggie's father to come to be there with Maggie after Diane dies.
Maggie returns home, and Meredith and Amelia sit with her and eat the last of Diane's lasagna in silence.