Confronted with Australia's first case of Ebola, the team races to uncover how patient zero, a U.S. Navy scientist, contracted the deadly virus, only to have their search for answers complicated by a top-secret military research agency as two of their own fight for their lives.

When a murder-accused American sailor is shot dead, the NCIS team investigates if an obsessed superfan from a popular true-crime podcast took justice into their own hands, blending true-crime obsession with high-stakes investigation in Sydney.