This whole day had gone from bad to bloody worse. Ruth was still annoyed at Harry for how things had gone at the dinner with Malcolm—though they'd sort of talked through some of it in the few moments they'd had throughout the morning, and at the very least he seemed to understand her point of view, though they'd not been able to actually do anything about it—and now Harry was angry at Ruth for having the audacity to do her job and give her informed and, frankly, expert opinion to the Home Secretary when he called her directly!

Harry was extra grumpy thanks to the presence of an FSB officer on the Grid. Ruth didn't like it much either, but it was the right thing to do under the circumstances. The Home Secretary was right, Russia was an ally and they all had to behave like it. Harry's old prejudices were not useful in the current climate. As a professional, Ruth had backed the HS. On a personal level, it made her chest ache to see how tense Harry was about all of this. He had good reason to feel as he did about the Russians. She did not begrudge him that. She knew, better than anyone else on earth, that Harry Pearce was a good, fair man. Not perfect by any stretch, but he never had any opinion or made any decision without very good reason. Ruth trusted his judgment more than she trusted any other person alive. She questioned him sometimes because she knew he needed it. Because she knew she was the only one who could question him. She had the seniority for it and the mind for it, and, of course, she knew she had his respect.

Only now Harry's decision to allow leniency on Azis Aibek was coming to bite them all in the arse. Ruth never would have said it out loud, but it was true. She had told him so, even if she understood his reasoning for allowing Aibek to live. Once again, they were dealing with the consequences, as they had to, but she would never deny that his kindness and decency were far more important than the problem they faced.

Thank goodness for Tariq being able to track Aibek. The field team, including Vincent from the FSB, was running all around London to get to Aibek. They'd cornered him on the underground, and Beth had the unenviable task of opening Aibek's discarded temperature-controlled knapsack to see if the Paroxocybin sample had been broken. But the bag was empty. He'd escaped their grasp and was now on his way to get the sample, surely. Tariq had found Aibek at Central College.

"Well, it needs to be stored at below zero," Ruth said as Harry paced the forgery suite between her and Tariq as they tried to come up with Aibek's next move. "There must be a lab in the building. Anywhere with a suitable freezer?" she asked Tariq.

"Dozens. It's the main science block for the university," he answered.

Harry looked up. Ruth watched him get his epiphany. "Check the faculty list," he instructed. "See if any of them were involved in the original Paroxocybin research team." Both Tariq and Ruth got to work.

It didn't take her more than a minute or so to find Doctor Kirby, who worked at Porton Down in the 60's on the Paroxocybin project. Harry leaned over her desk to read her computer screen as she explained, "Aibek's got to be there." It did not escape her attention that Harry had that little smirk on his face that he got when he was particularly proud of her. More recently, she'd come to know that it was also an expression that was a precursor to him kissing her. Obviously now was neither the time nor the place, but it pleased Ruth more than she wanted to admit to see that look on his face.

And with that, Lucas and Dimitri and Vincent were given their instructions to get to Kirby's office and corner Aibek. By the time Lucas called Harry, Kirby was beaten to a pulp and being wheeled into an ambulance. Aibek had already gone.

Once Kirby had been given a once-over by the medics, he was brought to the Grid. "Ruth, with me," Harry instructed. "I want you to question him to start. I've got a feeling you'll have a better rapport. I'll step in when I find my opening.

She gave a single nod, agreeing with his approach. She did tend to connect with the academic types, but obviously Harry was the better equipped between them to actually interrogate someone. Ruth followed Harry into the interview room. Inside, they found a beaten and bruised old man. Weary. But strong. Ruth could see it in his eyes. There was a determination there. Not a fire, but instead sturdy steel. This was going to be interesting.

Harry and Ruth took their seats. He introduced them to Kirby and then asked him to tell them about his experience with Paroxocybin.

"Paroxocybin was never intended to be a weapon," Kirby explained. "But once its potential as a nerve agent was recognized, all avenues of research were shut down."

"Until the '64 treaty?" Ruth prompted.

Kirby nodded. "We were told to wipe Paroxocybin off the face of the earth. I couldn't agree with that. It was a unique organism, and we'd hardly scratched the surface of its potential. Who knows what benefits it might bring?"

"So, you kept some back?" Ruth understood the good intentions that Kirby spoke of, of course, but the idea of flouting an international treaty that was designed to keep a deadly, terrible nerve agent out of the hands of Cold War superpowers was equal parts stupid and heinous.

All Kirby did was nod.

"And Professor Omasheva?" she asked.

"He felt the same. We agreed to do what we could to preserve Paroxocybin for posterity. Him in Azakstan, me here. It was the right thing to do." There was so much conviction in Kirby's calm tone. Ruth fell silent, not agreeing with his choices and not knowing what to say about it.

Harry quietly interjected, "Things have changed. We need to know where you're keeping the sample, Doctor Kirby." He leaned in, imparting the importance of his request.

"So you can start research on a cure for cancer?" Kirby asked sarcastically.

Ruth saw the small flicker of annoyance in Harry's face. "So we can prevent a known terrorist from acquiring a nerve agent."

"He won't find it," Kirby insisted with that same calm, confident tone.

"Aibek is a resourceful man," Harry countered. "He found the sample in Azakstan, and he found you.

"That was different. He had help. And I am not Professor Omasheva."

"He won't give up until he finds it. Don't you understand that?" Harry implored.

"The sample is quite safe."

Ruth could practically feel Harry's annoyance increasing from where she sat, but she kept her eyes trained on Kirby as Harry spoke, hoping to see some reaction, anything that might help them break through to him. "And when he does find it and uses it here or in Azakstan or in Russia, are you prepared to accept responsibility for the thousands of lives it will take?"

"He will not find it," Kirby replied simply.

"You're willing to risk it falling into the wrong hands?"

"I'm not willing for it to fall into any hands."

Harry let out a slow breath, which Ruth recognized as one of his methods of self-control and self-denial. He stood up and started pacing around the room. "You're what, sixty-two? Sixty-three? You can't live forever. You must have made a plan B. What if you got knocked down? Posterity's not much use when you're lying under a bus. You must have told someone," Harry said with increasing force.

"I told no one," Kirby maintained.

"I don't believe you."

"You're free to believe as you wish, Mr. Pearce. It doesn't alter the facts."

Ruth had been watching all this time and waiting for her opening. She knew she could get through to this man, somehow. He was an academic. A researcher. Concerned with humanity and what benefit his research could bring it. And for all his stoicism, Ruth thought she could see a sentimentalist inside Doctor Kirby. "You're concerned about what would happen to the Paroxocybin if you told us where it was," she commented, interrupting the increasingly frustrated back and forth between Harry and Kirby. "What if we gave you our word that it would be taken to Porton Down and stored safely?"

"Your word means nothing, however well-intentioned. People move on, regimes change. In a few years, weapons research would start all over again."

"We could guarantee its destruction. You could witness it," Harry offered.

"The last thing I want is for Paroxocybin to be destroyed!"

"You don't trust us to keep it, you don't trust us to destroy it. Meanwhile, you're willing to risk a ruthless terrorist getting his hands on it," Harry sneered.

"I've told you, the sample is quite safe," Kirby said once again. Nothing Ruth or Harry had said or done had altered his position at all.

Harry leaned over the table and hissed, "Don't be so bloody naïve." He pushed off the desk and went back to pacing behind where Ruth sat, still and calm and patient. Both of them were wracking their brains to come up with some angle they hadn't yet tried.

The door to the room opened and Beth entered. She handed something to Harry and whispered in his ear before leaving swiftly.

When she left, he walked to Kirby and handed over what turned out to be a mobile. "You have a call."

Kirby took the phone. It was his daughter, and Ruth and Harry both listened to Kirby's side of the conversation. Harry took his seat beside Ruth, and she was startled, actually, to feel that sudden sense of comfort at just having him close to her again. He'd not left the room at all, but having him sitting still, sitting next to her, it somehow felt better. Like they could be a united front again this way. Like when he paced and got frustrated, he was too distant for her to reach in the same way.

"I'm sorry," Kirby murmured to his daughter, clearly pained at whatever she had told him—likely that Aibek was there with her and threatening or harming her in some way. "Pactum serva," he said after a moment. And wasn't that interesting? All of a sudden, Aibek's voice came shouting over the phone, but Kirby just ended the call and put the mobile down, his expression never changing.

"Pactum serva," Ruth repeated. "Keep the faith."

Kirby gave an infinitesimal nod.

They didn't get a chance for much conversation after that. Tariq came to inform them that the field team had gone to Meg Kirby's house and Doctor Kirby's daughter had no survived Aibek's interrogation.

"She did not tell him," Kirby said. He hung his head in grief for the loss of his child.

"I know," Ruth said softly. "I'm very sorry for your loss."

Kirby did not respond.

Harry touched Ruth's arm lightly, indicating that it was time for them to go. She stood up and followed him out the door. She assumed they'd meet with the team in his office, but he stopped her before they turned the corner.

"Thank you," he said. "For everything you did in there. I always feel a bit better when I've got you next to me."

Ruth nearly smiled at that. For all the horror they still needed to deal with and the death of an innocent woman they couldn't prevent, she actually almost smiled. "We didn't get much out of him," she pointed out.

"No, but it doesn't change the fact that I still appreciate all that you do. No matter where we are," he added, his voice barely above a whisper.

He was trying. She knew he was, and she knew he would once she was able to properly explain her feelings to him. Harry always tried. But that was the thing, wasn't it? Harry always tried but in this instance, would he be able to actually succeed in making the necessary changes so that they could be together in the life they wanted for themselves? Ruth really, really hoped so.