As Dr. Sam Ryan returns to Cambridge, she struggles to balance her unstable family life with her work for the police department. Her first case proves harrowing enough as it involves a deceased child who has been abused.
Sam finds a connection between the deceased girl and a previous case from years ago, narrowing the suspect pool and aiding in the arrest of the culprit. Sam's life is put on the line due to a break-in at her house.
When a murder connected to the occult is discovered, Sam finds herself on the outs with the police department as she struggles to find evidence to connect their prime suspect to the crime.
With the suspicions around Sebastian Bird growing in the wake of another murder, Sam's conflict with the police department escalates, leaving her to look into an old case for clues to bring Bird down.
When a gay man dies under suspicious circumstances in police custody, the investigation takes a turn when the likely suspects being all officers of the law. Sam finds herself in a dilemma when an old face from her past makes a surprising appearance, much to her sister's resentment.
Sam's investigation becomes more complicated after a police constable is found dead. Danger lurks around Sam as a few hits are made on her life.
Sam's advice to one of her students backfires and leads to tragic consequences. Wyn and Sam's relationshiop is strained over the latter's relationship with Liam and their disagreement on the best course of action for their ill mother.
When the police identify the burned victim, their attempt to apprehend the suspect is rife with complications as they fear a violent escalation due to the suspect's mental health issues.