In Hampton, VA a girl is doing laps outside in the pool. Inside the house, the unsub is holding a young boy at gunpoint in front of his mother and sibling. The boy runs into another room and hides in the closet. The unsub finds him and fires 3 shots. The unsub walks outside and stands by the pool where the daughter is floating. The unsub gets into the pool and swims beneath girl, then pulls her down, drowning her.

Professor James Fallon studies the human brain and is giving a conference at a University closeby where the murders took place. Reid attends the conference, listening in as Professor Fallon explains the brain functions of serial killers.

Reid shows up at the home of the murdered family. He walks around inside the house and sees blood smeared across the kitchen floor. He looks at family photos on the refrigerator. Outside, Reid is joined by the rest of the team and Field Agent Anne Hudson. The cops found the family buried in the yard when the neighbors heard the dog scratching at the grave. The father is away serving overseas. Another family had been killed in a similar manner a year prior. The military is putting pressure on the police to find answers. “It’s a sign of remorse and when their done being remorseful, this will happen again,” Morgan says.

Hotch and Rossi are inside the house going over the crime scene. The children were carried out to the grave and the mother dragged. Hotch wonders why the unsub switched his method by drowning, not shooting the daughter, Lucy. Morgan and Hudson are outisde, watching the jets fly overhead. Hudson tells him that Langley’s 50th Anniversary Air Show is the next day. Morgan asks about the father of the first victims, Den Williams. After he discovered his family was killed, he signed up for another tour in Iraq and was killed a few months earlier from an IED. Morgan points out whoever killed the families knew the men were serving overseas. Prentiss comes out and says Laura Downey’s wedding rings are missing. They are going to check with the husband to see if any other valuables are missing. When the Williams family was killed, only jewelry and watches were taken. Reid says the unsub only took what he could carry which means he’s likely on foot. Rossi walks up and asks Hudson to see the photo missing from the wall. Hotch asks if Lucy was sexually assaulted because there was no sign of sexual abuse in the Williams case. Hudson tells him the coroner didn’t indicate in his report that there were any signs of sexual assault. The fact that the unsub dragged the mother out of the house in both cases and carried the children indicates it’s only one killer. There’s no signs of forced entry because Lucy was in the pool, so the door was unlocked. Garcia calls and informs the team that they got a call from the Virginia Maximum Security prison. One inmate, Karl Arnold (aka The Fox), received 2 envelopes in the last 2 days with media clippings of the Williams and Downey murders. The packages were signed by "an admirer." Four years ago, Karl Arnold a former psychiatrist, killed 8 families and kept the wedding rings as trophies. Morgan rehashes his interrogation of Karl Arnold to update Hudson. Morgan wants the information to be contained to the team. He sends Hotch and Prentiss to the prison to talk to Arnold. Hotch wants Garcia to check all of Arnold’s visitors since he’s been in prison. JJ gets a text message telling her Captain Joseph Downey has arrived at the station.

Back at the station, Hudson begins to tell Captain Downey about his family but chokes up. Morgan steps forward and tells him that his entire family was murdered by a serial killer. Morgan asks if they can call anyone or do anything but Downey just wants to go home. Downey begins to collapse but Morgan catches him. Downey breaks down and cries on the floor while JJ, Morgan and Hudson stand by helplessly.

At the prison, Hotch updates Prentiss on what to expect with Karl Arnold. Karl has a big ego, he will want to answer a question with a question. He will try and gain the advantage by asking Hotch why he isn’t wearing his wedding ring. Prentiss’s presence will throw him off but Arnold will want to describe every sexual act he did with the families to draw Prentiss into his fantasy. As they walk past inmates' cells, Hotch tells her to keep her eyes open and that Arnold will want to see the images of the children. Prentiss doesn’t want to do that but Hotch says it’s the only way they’ll get anything from him. Prentiss gets nervous when an unsub, who tore apart 14 women, slams into the glass and keeps screaming. Hotch tells her it’s reinforced glass, but it doesn’t ease Prentiss’ nerves. They finally get in to see Karl, who wasn’t aware Hotch was bringing a female agent. When Hotch goes to introduce her, Karl says he already knows who she is and everything about her.

At the station, Morgan thinks that if the unsub is working like The Fox they need to profile him like The Fox. The team goes over the details of the murders. Both families were attacked a month after the husbands had been deployed, long enough to make them feel comfortable that the fathers weren’t there. This unsub just walked in then dispensed of the family, living with them wasn’t part of the fantasy as it was with The Fox. Hudson walks in with the framed photo from the Downey house and hands it to Rossi. They were able to get fingerprints off the photo, which match those found at the Williams home. All the fingerprints were focused on Lucy’s photo and a gunshot was fired straight at the father’s picture. Morgan realizes most unsub’s don’t start with entire families, only one victim. He says there are more victims out there they just haven’t found them yet.

Hotch and Prentiss talk to Arnold. Hotch says it appears Arnold has a fan. Arnold corrects him and says it’s an admirer, big difference. Prentiss asks him if it’s the first time he’s been contacted by his admirer. “I have many fans, even my own website. Don’t you? You’d be astounded at some of the questions they ask. I make a log of all the things they ask. Would you like to read them?” Arnold says. Prentiss says she would love to. He points to the log book and Prentiss reaches for it, but Arnold leans forward and smells her. Hotch grabs the book and hands it to Prentiss. She puts the book aside and says, “But maybe later.” They bring up how the admirer is taking wedding rings but not for the same reason. “Like how you took all of mine?,” Karl asks Hotch. “You took mine, but I see you lost yours,” Karl says. Karl wants to know how Hotch lost his ring, and mocks him - saying it was a casualty of the job. Hotch says his job is what put Karl in prison. Karl points out that the children suffer the most. He wants to help Hotch but he wants to see the photos first. Prentiss asks to talk to Hotch and Karl wants to know if she has a problem. Prentiss doesn’t want to show Karl the photos, she isn’t happy using the images of children as a bargaining chip. Hotch tries to convince her of why they need to do it but she isn’t comfortable. Hotch tells her she doesn’t have to do it but she says she does. Hotch tells her that he will get Karl comfortable and then leave the room. Once he does, he wants Prentiss to stay on script no matter what Karl says or does, because they need to know why he killed the families.

Garcia is talking to JJ, she says only a few whack-jobs have contacted Karl other than the admirer. Garcia tells JJ she is unable to make a connection between the families, the only connection they had was the military and their means of communication. JJ asks Garcia about getting into the military's system but Garcia won’t hack into the Military’s system because she likes her job. JJ says she’ll see what she can do on her end.

The rest of the team discuss the two cases. The fingerprints in the Williams house were mostly concentrated in the daughter Karen’s room, like she was isolated. Lucy Downey had already solved that problem for the unsub by being outside in the pool. Reid points out that Hotch was right, it’s probably a signature. JJ is on the phone and gets permission for Garcia to gain access to the military records for the fathers.

Prentiss and Hotch return to the visiting room. They have Karl uncuffed and Prentiss puts the photos down for him to see. Karl smiles when he sees the family photo with the bullet hole in it. Hotch walks Karl through the crime scene. Karl informs them that the killer knew everything about the family, their every move in order to achieve what he needed. He then points out that the “how” is what the team doesn’t know. Karl says he watched the families for weeks, and that this unsub didn’t bother with them that long so he couldn't have enjoyed them. Karl doesn’t understand why the unsub didn’t separate the children, as it would have given him more control. He then wants to know how Lucy died and runs his finger across her picture in the family photo. He wants to see Lucy’s crime scene photos but Prentiss stops him from getting them out of the folder. He says to feel the life leave the daughter’s body means everything to the unsub. Prentiss tells him there’s no sexual gratification with this unsub. “At least I spared the fathers the grief of living,” Karl smugly tells them.

A woman pulls up outside of her home in a minivan and gets out with her son. Her daughter, Dani is upstairs looking out the window with the unsub who has a gun aimed at her. The mother walks into the house with groceries and her son, who goes running off as the mother calls for the daughter. She hears heavy breathing and the daughter calls her name. The mother looks up the stairs and drops her grocery bag as she sees the unsub holding her daughter at gunpoint.

The team pulls up the crime scene. They go inside and find the same scenario. The family photo, the father’s photo with the gunshot to it, and the family buried out back. The girl was suffocated, not shot. The father is serving in Afghanistan. Something has dramatically changed for the unsub to move up the time table from a year apart to 3 days. The team believe it’s a stressor and then realize it’s tied to the air show.

Prentiss is talking to Karl alone, and he realizes the unsub has killed again. He thinks it’s lucky for him because it leaves him alone with Prentiss. Karl thinks they have to wait now and see if his admirer contacts him. “Yours is one of the first cases I studied,” Prentiss says. Flirting, she tells him she’s been fascinated by him since. He smiles and she smiles back. “And now you want to know what I did to the children. Don’t you?” Karl asks. Prentiss says she does. He offers to show her exactly what he did to the children, she wants him to tell her instead. “Children are so precious, so clean. But they need guidance, especially the girls. They have much more to lose than boys. It’s a fact the female body can handle pain much better, “Karl says. He showed the girls what men, the fathers and brothers, are capable of. Watching from another room, Hotch is on the phone with Morgan and says if the air show was the stressor the unsub doesn’t fit the same profile. Hotch reassures Morgan he couldn’t have done anything to stop the latest murders. Karl’s admirer has nothing to do with the killings. Morgan wants Hotch to stay and find out what he can to stop the murders. Hotch hangs up and listens to Karl admit to Prentiss that it amazed him that once he killed the children, the fathers didn’t fight the inevitable, dying.

Garcia is going through the Williams information, she hasn’t been able to find any connections between the killings or a hit on the fingerprints in any database. Reid, remembering the conference he attended, points out the photos of the grave and asks the team what it reminds them of. JJ says, “Mass graves.” Reid thinks the unsub was born into conflict. They have never seen anything like this before so they have Garcia do an international search.

Hotch tells Karl he’s surprised that he told the truth, Karl says it took a good woman to make him come clean. Prentiss says Karl told her how, now she wants to know why, he killed all those families. All of Karl’s motivations were about sex, motivations he learned from his father. “You really have done your research on me, Emily. I’m flattered,” He says. Prentiss tells him that by killing the fathers last, he was killing his father and himself, over and over again. Karl looks at Hotch and tells him it’s not over, at least not for him. Something dawns on Prentiss so she looks at Hotch, she tells him that in Karl’s case, he killed the father’s last but in these cases, the unsub kills the daughters last. They then realize that the killer is a woman. When Prentiss leaves to call Morgan, Hotch asks what Karl meant when he said it’s not over for Hotch. Karl tells him he doesn’t see it but he will. The unsub is just getting warmed up.

Morgan gets off the phone with Prentiss and tells the team that the unsub is a woman. Garcia gets a hit from Interpol on three unsolved cases with the same fingerprints. The woman was born in the middle of conflict in Bosnia and moved to the U.S. within the last few years. They believe she is in her late twenties.

Hotch doesn’t believe the woman/unsub has anything to do with Karl. Prentiss is upset about getting intimate with a killer, as she flirted with him to gain information. She’s feeling uneasy about what she had to do. Karl calls out for Hotch, telling him he has one final thing to share with him. Prentiss wants to get it over with so they head back into the room with Karl.

The team gives the profile to the local agents. Meanwhile Garcia is looking at the family photos and makes a connection, all of the families uploaded their photos to Photobug and printed them. It’s a great way for military families to stay in touch. Garcia ran down the new profile against Photobug’s employee database and came up with a name, Miranda Jakar who was an orphan from Bosnia and later adopted in the middle of conflict in Croatia. The team goes to Miranda’s home and nobody is there, but they find photos of the previous families and also a photo in the printer of the next family she's targeted.

Hotch and Prentiss are still talking to Karl. He can’t give them more information on the case but believes the team hasn’t found his admirer. Hotch says they will find him but Karl says, “No Agent Hotchner, I think he’s already found you.”

The team breaks into the home of the next family. The mother and son are sitting on a bed shaking. Miranda comes from across the room and tackles Morgan, knocking his gun out of his hand. They fight over the gun until Morgan gains the upper hand, turning the gun on Miranda, killing her.

Back at the Prison, Hotch is flipping through the file. He pulls up Karl’s notebook and flips through it. Prentiss is worried about what is going on and calls Hotch’s name questioningly. Karl laughs as Hotch comes across an article about his attack with a sign from Foyet. Prentiss realizes what is going on as Hotch grabs his stuff and heads out. Karl laughs saying, “He knew you’d come.” Angrily, Hotch heads out of the prison with Prentiss following.