在第四季的首播集中,疾病大流行已延烧数月,剧集将透过尚恩墨非的观点,阐述全球医务人员正面对的挫败感,令人喘不过气的不确定性、危险和失败。Lea and Shaun's new relationship will become tested. Park gets ready to move back to Phoenix. Morgan puts herself and several members of the staff in danger. Claire continues to work through her grief from the death of Melendez.