8:23 pm (CT) | Above Iowa

In David Rossi's experience, one of the best gauges of an agent's personality was how they reacted when they witnessed a gruesome act unfold in front of them; how jaded they were.

The mood was somber in the plane, leaving Rossi to recall his observations throughout the case.

Yesterday, 3:56 pm

There was zero time to waste. The locals had waited long enough to call the FBI in, and the local FBI field office also stalled calling the feds. Now the BAU was dealing with seven bodies and zero evidence. The plane had landed and no more than two minutes had passed when the team ran out and hopped into cars.

Rossi and Prentiss made their way into the precinct, exchanging very few pleasantries while the rest of the team dealt with their tasks. While the two oldest agents studied victimology, JJ and Morgan visited the latest crime scene and Reid went with Bell to the M.E.'s.

As soon as everybody had returned, the team immediately jumped into deliberations and sharing their findings.

"M.E.'s report shows abnormal levels of glucose…"

"An aberration in the routine of victim five…"

"Frequented the same cafe…"

"Geographic profile shows overlap in the fifth district…"

It was a frenzy of activity-coming and going with minimal rest. They worked tirelessly through the night. An eighth body would mean political suicide for the Bureau, something that law enforcement could not afford amid a recent wave of anti-police movements.

Today...

Late into the night, a breakthrough was made. Just as Reid finished up the geographic profile, Garcia came up with something on her deep background searches, Emily and Rossi figured out the common denominator, and Bell connected it all with Morgan, while JJ finished up the missing piece.

Garcia started. "All of them took a flight in 2010 that passed through Omaha."

Reid sprung up, lightbulbs going off, "That works with the geographic profile! It's the most optimal route for their flights, considering tailwinds-"

"Wait-Omaha, isn't there a federal correctional terminal there?" Rossi asked.

"All federal prison transfers cross-country pass through Omaha International as well!" Emily exclaimed.

Morgan got where she was going with her train of thought. "Baby girl, cross-reference federal prison transfers with the dates that our victims passed through Nebraska…"

Furious typing was heard while Garcia tried to find a possible perpetrator. "No luck, my lovelies. No same prisoner passed through on all seven dates. In fact-" more typing "-no same prisoner ever passed through on even two of the dates."

The team fell into a contemplative silence. Bell looked at Reid's map and the dates, and recalled what Rossi and Emily said. Something clicked.

"Wait! Penelope, run the same search but with US Marshals instead. Since Marshals escort detainees, they would also frequent Omaha!"

He fell back into defeat when this too, yielded no results. He knew the Marshals had something to do with it, he just couldn't figure out what. And having worked with Marshals at Interpol, he knew without a search parameter, they'd never find him.

JJ then piped up with a morsel of brilliance.

"Did you just search for Marshals who participated in inmate transfers, or did you search with Air Marshals too?"

Garcia expanded her search. Boom. They had their man.

"30-year-old Tristan Wallace-he's been a Marshal for five years. He was involved in multiple skirmishes with passengers and convicts over the years-seven reprimands. And guess what dates they were on, my sweets?"

"The dates that our victims came through Omaha?" Reid supplied.

"Correct, Junior G-Man!"

"So why them?" asked Emily.

"Think about it, Prentiss-seven physically fit men who did nothing to break up the fights or help Tristan. This unsub's an injustice collector," Bell answered.

"When does he pass through Omaha next? We have to be ready for him," noted Rossi.

"According to our buddies the Marshals, your Tristan Wallace is scheduled to fly into Omaha tomorrow at around 4:30 in the afternoon, crime-fighters!"

"Time to deliver the profile," JJ said, glancing at the clock. "Actually, speaking of time, let's wait till the morning shift rotates on in an hour and a half."

In the meantime, the team devised a plan of action to apprehend Wallace without endangering any member of the public. This automatically ruled out arresting him in the airport. Considering he would be heavily armed, an apprehension in a deserted locale would be ideal. They could not let him get home, lest he reach for more dangerous weapons.

Little did the BAU know everything would be as far from ideal as possible.

5:16 pm | Eppley Airfield, Omaha

From the moment Wallace disembarked, the BAU had eyes on him. First with the DHS and TSA agents patrolling the airport, to the undercover FBI agents tailing him after he hopped into a car, to the NSA satellites keeping an eye on him from above.

Unfortunately, he shook them. Being a US Marshal, he had unfettered access to quite a few judicial documents, many of which identified distinguishing features of plainclothes federal agents, or the flight paths of NSA satellites.

The one thing they desperately hoped would not happen, happened. He swerved, he ran over things, he abandoned and stole cars like it meant nothing, with no regard for life or property. Evasion was his only goal, and he achieved it.

He got home. The place had obviously been ransacked by the FBI and its many firearms confiscated by Marshals, but god only knew how many more weapons he had hidden away in his house's numerous nooks and crannies.

The surveillance agents on Wallace's street only noticed he was home after he deliberately turned on a light in a conspicuous front window. No one knew how long he had been in there. Even if Tristan was sorely outnumbered, nearly 50 to 1, he still had the upper hand.

And unfortunately, it being nearly six o' clock on a Friday evening meant people were out and about. The worst-case scenario had presented itself. There was no way they could wait him out-a standoff would take much too long. Going on the offensive was an absolute no-go; he'd blow himself and numerous federal agents and local officers up without hesitation.

The ball was in Tristan's court. And to his credit, Rossi remembered bitterly, he played his hand perfectly.

A man all-too-familiar with negotiation tactics and government protocol took civilian hostages yet never left the house; he aimed a long-range LMG at an obviously-occupied civilian house and forced the BAU to negotiate for a family of five.

They knew he was a ruthless sociopath with zero regard for his life and anyone else's but even in their wildest dreams they did not imagine he would do what he had.

Nearly 20 minutes into a back-and-forth with Tristan, he stood smugly, speaking condescendingly to those who felt there was no way out below him; the law enforcement officers simply trying to save an innocent family.

"You will let me go. You will remove all surveillance on me. You will take off any alerts on my name or identification. You will not pursue me. If any of these conditions are not met, that family will be meeting their maker soon."

"Tristan, listen to me-" Rossi had tried.

"No. We're done here, SSA David Rossi," Wallace said mockingly.

In their hearts, they knew he was right. They simply could not risk the lives of fifty-five people by not acceding to Tristan's demands. Even if the SWAT snipers could get a shot on him, the remote detonator in his hand would activate the multiple short-range missile systems and LMGs that he had set up the moment his pulse was no longer detected.

So when they let him walk by, an evil grin on his face toward his car, the BAU expected him to leave, leaving them to their own devices.

That was not what happened.

Tristan had left peacefully. The officials present on the scene waited a minute before breathing a sigh of relief.

That was when all hell broke loose.

8:27 pm

Rossi recalled with great sadness the carnage. The bloodbath. The piercing sounds of bullets and missiles going off. Looking at 23 corpses, 23 people who would never say an I love you again, a toll that would undoubtedly increase in the coming days. But more than anything, he recalled Bell.

The look of utter detachment, a face devoid of all emotion as he methodically scanned the hellscape in front of him. His eyes showed a man who'd seen this particular scene one too many times. David watched as hours later, the first semblance of feeling creeped onto Bell's face.

Long after he'd cleaned off the flesh, blood, and brains of the people he had known for too short a time, Rossi watched the anger, the frustration, the determination, the regret flash through his eyes. But the man was too skilled to every bare the sheer amount of pain he truly felt.

In David Rossi's experience, one of the best gauges of an agent's personality was how they reacted when they witnessed a gruesome act unfold in front of them; how jaded they were. In the aftermath of Tristan Wallace, he realized just how broken a man Foreign Intelligence Officer Bell was.