Ingrid's lies come back to haunt her when her sister Gigi needs to be treated by the team after she develops side effects to the secret treatments Ingrid put her through. Also, Watson and Mary bond over a tragedy.

Watson confronts a traumatic event from his Army days that still weighs heavily on him when his Army veteran friend's wife reaches out begging for help when her husband is seemingly having a psychotic break. Meanwhile, Shinwell is asked for one last favor by Moriarty.