The episode begins with Erin, with a bleeding nose, walking on the streets of New York. Her head is spinning. At that moment, a man comes up to her and holds her. He asks her if she really thinks that her team would come and save her. She tells him that she knows they would. The man then talks about how her drinking got in her way and how her husband tried to help her with her drinking problem. He also knows that her children played second fiddle to her ambitions. Erin tells the man that she is not able to see. At that moment, Erin’s phone rings. The man checks the phone. It is Rossi. He disconnects the call.
JJ calls her husband and tells him that the Replicator is back and she has to be in New York for a while longer. Garcia calls JJ to check if they are alright. Garcia is a mess and is in tears. Kevin tries to figure out how the Replicator got into the systems. They realize with a shock that the Replicator accessed the system from Garcia’s house. The team is on full alert. Everyone is fine, but they learn that Erin is missing. Hotch asks Rossi if Erin had started drinking again. Rossi tells him that Erin has been sober for over a year. The window of Erin’s hotel room is open. Rossi is sure that the Replicator has taken Erin. He goes to check the roof. Hotch tells Reid and Alex to check the security footage. Morgan, JJ and Hotch check the stairways.
Hotch receives a call from Erin’s cell. It is the same man who has Erin, the Replicator. Hotch, Rossi and Morgan manage to locate Erin. It looks as if the Replicator wanted them to find her. Hotch rushes to Erin. Erin tells him that the Replicator held a gun on her head and made her drink. She also tells him that he knows her family. Later, Reid tells the team that the Replicator hacked into at least two dozen systems and erased all security footages. He also managed to get into Garcia’s house which proves that he is bragging. Erin dies. Rossi tells Hotch that he wants to take her to Bethesda. Hotch tells the team that the Director has given them 24 hours to solve the case. Rossi tells Hotch that the Replicator tried to humiliate Erin by forcing her to drink.
He feels that Erin’s children would never believe that Erin was “forced” to drink alcohol because they know that she was an alcoholic. Rossi decides to take Erin’s body to Bethesda. Later, the team arrives at their HQ. They are surprised that the Replicator knew the guy who killed Hotch’s wife. Hotch tells Garcia to tell Kevin to analyze every pixel of the photographs taken by the Replicator. They also feel that the Replicator was obsessed with Erin, and probably she was always his first target. Hotch wants Garcia to find out how long will it take to drive to all the murder locations. He is sure that the Replicator brought the fight to New York for a reason. The ME tells Rossi that Erin was given the meth-ecstasy combo, but it didn’t cause her blood to boil like the other New York victims. The exact breakdown hasn’t arrived yet. She then shows him the marked carved on Erin’s wrist.
It was carved anti-mortem. It is the number 8. Reid thinks it could also be the infinity symbol. If it is the number 8, then it could mean that Erin was the Replicator’s eighth victim or it symbolizes that she was the ‘unofficial’ 8th member of the team. Garcia tells them that looking at the way the Replicator managed to get past all the security systems, he has got to be on the inside. It is then seen that the Replicator enters his office with Kevin and one other guy. Garcia was right. The Replicator works for the BAU. He also readies an envelope for Rossi and marks it as ‘confidential’. Later, the team wonders why the Replicator targeted Erin. Hotch thinks that Erin started her own investigation on the Replicator because the Director did not want the team to pursue the Replicator case.
He feels that the “8” was a part of her plan to catch him. Hotch takes Erin’s laptop to Kevin and tells him to find out as to who was on the distribution list for his case reports. Kevin sees that the last report was sent on the Detroit case. Hotch reads the report and sees that Erin had amended the report and written that there was a figure 8 carved into the victim’s wrists. This had not happened. This also means that one of the people who read the report has to be the Replicator. Kevin checks and tells Hotch that two other people read the report. He also tells Hotch that ‘he is going to need a tie’. Later, Hotch meets Senator Cramer. He tells Cramer about Erin’s death and also that the Director is keeping this issue contained.
He wants to know who else had access to the case reports. He tells Cramer that the other person could be in one of the highest levels of the Justice system. The team tries to relate all the replicated cases. They get stuck on the Seattle case. Garcia manages to get someone from VICAP to have the details of that case faxed to the office. Rossi arrives at the office and walks into his cabin. He finds an envelope on his desk. It is marked as “confidential”. Hotch gathers the team and tells them that at least a dozen federal employees read the case files and each employee has two assistants. This means there 36 people they need to look into. Alex shows Hotch the Replicator’s first case. She thinks that the Replicator started all of this when she joined the team.
Morgan goes to check on Rossi. Rossi looks disheveled. He pulls a gun on Morgan. Hotch arrives and Rossi tells him that Morgan’s DNA was on the glass that cut the 8 on Erin’s wrist. Hotch notices that Rossi’s nose is bleeding. He realizes that Rossi has been drugged. He calls the paramedics. Hotch tells the team that the report must have been dusted with whatever that was used for Erin. Morgan tells the team that Erin was killed with a chemical cousin of “Doctor Death”. The Replicator altered it for Erin so that the torture would be longer. So the Replicator is a biochemist, a computer hacker and a federal agent. They check the security footage of their office. They see that the Replicator enter Rossi’s office, making sure that the camera doesn’t capture his face. He signed in as Adam Worth.
Later, Alex tells the team that the Replicator has targeted everyone except her. This means that she is the part of his end game. Alex tells them that she and Erin had some issues about the poisoning case in New York which led to her professional setback. This means that the Replicator also must have suffered some professional setback because of that case. Garcia arrives and tells them that there were two agents in New York in 2001 during the poison case, one of them is dead and the other one is John Curtis. It is seen that Curtis is the Replicator. Alex knows this guy. She tells the team that he was a quiet but brilliant man. His passion was biochemistry. Elsewhere, Curtis who is monitoring the team’s movements, watches the team leave the office. He puts some stuff in his bag and leaves.
Garcia tells the team about a plot owned by Curtis. She also tells them that Curtis suffered a setback during the poison case but he quickly worked his way into the Justice department. The team gets into the choppers and leaves to get Curtis. Hotch tells them that they will go separate ways so that they could land on the opposite sides of the property. Curtis intercepts the signals of Hotch’s chopper and jams it. They crash but no one is hurt. JJ and Morgan arrive at the crash site and see that Hotch and Reid are safe but Alex is missing. They also find some equipment inside the chopper. Kevin and Garcia figure out that Cutis knew that the team was coming for him and how they were getting there. Kevin tells her that there was a system override which happened within a five mile radius.
Next, it is seen that Curtis has abducted Alex from the crash site. He brings her to an empty house and chains her to a chair. Alex wakes up and remembers that there was some gas released into the chopper that rendered everyone unconscious. Curtis tells Alex that she took away his chance of working with the BAU. He is also pissed that he was transferred to Kansas after Erin screwed up. The team arrives at the house and finds Alex, but Curtis is gone. Alex tells them that Curtis used 8 locks because there used to be 8 of them, but there are only 6 keys, which means two keys will be used twice. The letters on the keys say ZUGZWANG. Reid thinks that this is too easy. JJ searches the house and finds hidden explosives and the timer is already on. There are three minutes remaining. Morgan and JJ warn the others who are trying to rescue Alex.
Reid tells them that ZugZwang actually means not to move at all. Reid is about to tell Alex not to get up, but it is late. Alex gets up and the door gets locked. He tells the team that there was a pressure sensor on the chair. Curtis checks his phone and the sees that the signal has been interrupted. It is Garcia and Kevin. She tells Rossi, who is now in Curtis’s house, that she cannot hold the signal for long. Rossi holds Curtis on gunpoint and tells him to walk. Curtis manages to get the door locked. The signal is back on.
The rest of the team manages to get out of the house, but Rossi is still inside and there is less than a minute left for the explosion. Inside, it is seen that Rossi has tricked Curtis. He had blocked the door with Erin’s sobriety coin. He opens the door and quickly leaves, and Curtis ends up getting locked inside. The whole team is now safe. The house explodes. Next, the team attends Erin’s funeral and later have dinner together. The season ends.