Based on his nightmares, Reid decides to stay in Las Vegas to probe deeper into his nightmare, specifically if his father, William Reid, who abandoned him and his mother when he was a child, was the murderer of six-year old Riley Jenkins when Reid himself was only four. Rossi and Morgan decide to stay and assist Reid. Reid learns that his father has been living just outside of Las Vegas all these years. Upon meeting his father, Reid confronts him with his suspicions. Reid Sr. denies any involvement or knowledge of the murder. Immediately after Reid confronts his father, an anonymous source provides another suspect for the murder. After going into hypnotherapy, Reid also thinks that his mother, Diana, is suppressing some memories from an incident surrounding the murder. Diana decides to go off her medication so that she can remember what happened the night that caused her mental instability. Meanwhile, J.J. goes into labor, three weeks before her due date.