A mysterious case involving a young orphan, Ava, reminds hardened National Crime Service investigator Victoria Woll of her own painful childhood; a dark secret about Victoria's past jeopardizes her future.

The threat against police officers is heightened after a retired cop and recognized hero is killed; Victoria gets an ominous warning from a fellow prisoner.

The team is tasked with solving the murder of a nurse at a high-security psychiatric unit; Victoria is forced to confront her inner demons when she goes undercover and gets admitted as a patient.