Woman walks into the station covered in blood, carrying a gun, and saying she killed someone. Unfortunately, the trauma of what she did caused her to forget who she is or who the victim is. The team tries to unravel this bizarre case as they deal with the loss of close friend and colleague, Det. Barry Frost.

When a man is found murdered inside his supposedly impenetrable doomsday fallout shelter, the squad must figure out how and why he was targeted. Jane finds it difficult to focus on the case when she discovers Korsak is looking into retirement and Frankie is keeping a secret of his own.