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.

While Addison deals with the unwelcome arrival of her father, Cooper is arrested because he refused to cooperate in a case involving a longtime patient. Meanwhile, Pete will stop at nothing to keep a terminally ill patient alive for as long as it takes for him to meet his new daughter.

Maya shocks Sam and Naomi, while Pete and Fife disagree on patient care.

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.

A husband's decision to pull the plug on his pregnant wife is overruled by a judge, forcing the hospital to keep her on life support until the fetuses she is carrying as a surrogate are able to survive. Meanwhile, Naomi feels betrayed after learning of Sam and Addison's feelings for one another, and she turns to Dr. Fife for support while William is away on business. And unable to cope with the tension, Addison takes the day off with Pete and Lucas.

When famed neurosurgeon Dr. Ginsberg and her team pay a visit to St. Ambrose to save the life of Kayla, Addison is shocked to see Amelia Shepherd - Derek's younger sister on the team. But Amelia's presence causes strife between Addison, Sam and Pete when she claims she can save Kayla's life after Dr. Ginsberg declares nothing can be done. Meanwhile Charlotte seeks from Cooper's with a sex education seminar for the elderly that only leads to more tension between the two, as they try to figure out how to work together.

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.

A couple wants to harvest eggs from their unborn child who is not going to survive, and the doctors cannot agree what the right path is; meanwhile, Amelia tries to comfort a friend while waiting for test results for Huntingtons disease.

The day has arrived for Cooper and Charlotte to marry, but not everyone is in a celebratory mood, leading the couple to second-guess their wedding plans. Meanwhile, the doctors of Oceanside Wellness are torn between the future of their practice and protecting one of their own, as an investigator is sent to question them about Violet's breach of confidentiality case.

When Betsey returns to the ER for a second visit, the concerned Oceanside doctors start investigating the foster family. Amelia struggles to stay sober while Naomi announces a life changing decision affecting her family.

The fate of Oceanside Wellness is on the line as the doctors decide if it's time to dissolve the practice. Addison's new admirer makes an enticing offer and things hit close to home for Charlotte with her latest case.