Shaun and Lea adjust to parenthood as they debate the importance of schedule and routine for Steve. Meanwhile, Shaun takes on his first case back at the hospital with two baby patients in need of the same heart.

Shaun struggles to accommodate the newest member of his surgical team, Charlie, who interferes in a patient's relationship with his daughter; Park tackles a tricky brain tumour; Lea and Morgan adjust to motherhood.

Shaun continues to be tested by Charlie when their newest case prompts her incessant stream of questions - all in pursuit of an answer; Morgan struggles on who to name as guardian for Baby Eden should anything happen to her.

Shaun and Lea struggle to balance their parental duties with their personal lives. Meanwhile, Park and Morgan try to find the time and space to reignite their romance amidst the demands of parenthood and work, and Lim's mother makes a surprise visit.

Asher's views on the construct of marriage complicate his future with Jerome. Meanwhile, Asher also briefly revisits his religious past to aid a patient's conversion to Judaism for his fiancée.

The team must deal with a mass casualty event that forces them to put aside their emotions following a recent tragedy.

Shaun and Jordan's patient is in dire need of a kidney transplant. When they find the perfect donor, they also discover that he believes he is Jesus which could compromise his ability to give consent to the surgery.

Shaun, Jared and Charlie's young patient need his parents to agree on an important medical decision that could greatly improve his health; however, his parents are unable to agree on the correct path which spurs the team to try and intervene on behalf of their patient.

Dr. Claire Browne returns from her work in Guatemala for a personal medical examination. Elsewhere, Dr. Glassman struggles to manage Hannah, who remains unresponsive to his attempts to help. Park seeks out the perfect last-minute wedding location.

As the doctors consider their futures, they work together to solve one of the most important cases of their careers.