Addison sends a pregnant woman to St. Ambrose for help from Noah after she experiences heart complications. Meanwhile, Sam begins to rethink his friendship with Naomi; Pete and Lisa's relationship becomes increasingly complex; and Sheldon takes a stand.

As Violoet chooses between Pete and Sheldon, she must also deal wtih a grief-stricken patient. Meanwhile, Dell worries about his daughter when Heather returns to town and Naomi debates moving to Pacific Wellcare.

The doctors venture into controversial territory when an unexpected new hire at Pacific Wellcare causes Naomi to struggle with the idea of genetically designing babies and Violet makes a sudden decision to try electric shock therapy on a patient. Meanwhile Addison somehow finds herself alone and with a cat.

When Naomi refuses to help plan Maya's wedding, Sam convinces Violet to help her. Meanwhile the tension between Addison and Sam deepens when they treat a suicidal patient and Cooper and Pete treat a girl with a questionable bite mark.

Things get too close for comfort when Addison, Pete and Sam must come together on a complicated case involving a dad-to-be who comes down with tuberculosis and threatens the future of his new family. Meanwhile, with Violet still gone on her Costa Rican escape, Sheldon takes over helping one of her patients, Natasha, to get over her crippling fear of flying, and Naomi finds herself in a bit of a love triangle of her own.

When Addison's patient and the life of the three unborn babies she is carrying as a surrogate hang in the balance, Sam's new girlfriend, Vanessa, and Addison are sharply divided on the course of treatment. Meanwhile Cooper seeks Sheldon's help with a young patient, but their personal quarrels over Charlotte get in the way, and Naomi has a dilemma of her own between William and an unexpectedly charming Dr. Fife.

Naomi begs Fife to use his still experimental treatment to help William's advanced ALS. Violet and Amelia treat a woman with a brain tumor, while Sheldon decides to vie for Charlotte's affections.

Maya and her unborn baby are fighting for their lives on the operating table, and Addison, Amelia and Fife try everything humanly possible to save them. Meanwhile, Sam operates on an incoming crash victim and later makes a grim discovery; Cooper makes an ill-timed but valiant effort with Charlotte, and the staff’s world gets rocked by an unexpected death.