"We've found something weird."

Jane and Maura both sat up, looking intently as the technician spoke.

"I went through Harriet's laptop. Detective Greenly wondered if, since she was the most recent person to start asking questions about Mercurius, she had had any contact with this professor."

"And?" Jane rubbed her hand over her scar.

"And she did. There is an email, only one, from Harriet to Professor Rusieuc. She says she received the email address from a friend."

All eyes in the room turned to Maura, who shook her head. "Not me."

"No. But possibly Rachel," Detective Greenly concluded. "We will confirm."

"Anyway, I used the email address to back-trace his IP address."

Everybody sat, waiting for the technician to explain.

"It's not entirely conclusive, but the IP address is from Victoria College."

"Kaplowitz's office?"

The technician and Greenly nodded. "Exactly."

Jane ran a hand through her dark hair. "So what now? Do we investigate every member of staff? Find out where this professor guy was working?"

Greenly shook his head. "I already called. There is nobody by that name registered with the university. There never has been."

Maura opened her mouth to speak, but Greenly held up his hand. "And, before you say it, I've checked with Oxford Brookes University at the top of the hill. They don't have any records either. In fact, nobody outside of the Bletchley society and those of us involved in this investigation seem to have any knowledge of this guy at all."

"So the professor's a cover? A fake?" Greenly nodded at Jane's suggestion.

"That's the theory."

The technician opened his laptop, and began to type in the professor's name. "I'll show you what happens when we search."

The technician typed a number of variations of the professor's name into the syntax window and pressed 'enter'. As thousands of databases and resources were scoured, only a handful of results appeared.

"Oxfordshire police." Jane shook her head. "The only results are from what we've written about him ourselves. Shit."

The technician closed his computer, and began to pack away his notes. "Sorry, guys. But whoever this Professor Marko Radoslav Rusieuc is, the answer isn't online."

"Wait!"

Jane jumped in shock as Maura's hand wrapped around her wrist.

"M. R. Rusieuc. That's it!"

Leaping to her feet, Maura grabbed the technician's papers and pulled a pen out of Detective Greenly's pocket. Feeling the confused stares of everyone on her, Maura smoothed out the back of the paper and began to write.

"Oh my God." Jane's hand rested against her temple. "It's all just part of the game."

"He's playing us. This… this wordplay. It's Kaplowitz. He told us this is what he had taught Rachel to do. Pen and paper codes, word games. It's him, Jane. He's got to have something to do with this."

"Could it be one of his students? If he taught Rachel, he could have taught anyone else how to do this. We need to speak to him. We need to find him." Jane couldn't help but let her agitation be known. They had spent a whole day focusing their search on someone who didn't even exist. Time was running out, and with Harriet still in hospital, they would have to find the answers themselves.

Detective Greenly placed a protective hand on Jane's shoulder. "We'll find him. I've been told what you two can do together. I've got every confidence that this Kaplowitz guy won't get far."

"Well" Jane smiled at the older detective. "We'd better get started, then."

/

"Do we have all of Rachel's notes?" Jane asked from across the large conference room the police department had offered to the detective and the doctor.

Maura shrugged. "I think so. I mean, the police have given us everything they had, and Harriet had taken everything else."

"Okay. I just can't work out how Kaplowitz is connected to all of this. Not really. I mean, the guy's a history professor. A nerd. How has he managed to get himself caught up so deep in the middle of an international ring of hitmen and criminals that he has a fake identity and has murdered two people?" Jane thought for a moment, smiling deviously to herself. "Although let's not forget that he's not the first nerd to get caught up in murder, is he, Dr Isles? Or in organised crime?"

Maura found the closest piece of unused paper, screwed it into a ball and threw it at the detective. "If you dare bring any of that up in front of these people, I will call your mother and tell her why you're really here."

Jane pouted comically. "Fine. Thanks for ruining my fun."

Maura smiled. "Well, it's not fun for me. Pick on someone your own size. Or, better still, pick up the papers in front of you and help me solve this murder."

"Yes, mistress."

"Less of the mistress. I don't care what you're into in the bedroom, but it has no place at work."

Jane raised an eyebrow at Maura, who was now blushing slightly, but chose to stay silent on the matter. It was far too soon, not to mention inappropriate timing, to be talking about being intimate with one another. Even if she had already declared her love for the blonde doctor, everything else would have to wait until they were definitely safe and Kaplowitz- or whoever was truly behind the operation- were locked away.

"Anyway… back to the case."

"Back to the case" Maura repeated. "Maybe we should go back to the start. Back to Rachel."

Jane nodded, leaning back into her seat. "Rachel Maloney was researching at Bletchley. She had contact with Martin Richards, with the Bletchley Historical Preservation Society, with Kaplowitz and, possibly, with the fake Professor Rusieuc. She's also our connection to Harriet."

Maura nodded, listening intently to Jane's explanation. "We know that Rachel had visited Bletchley, and that she had been in the archives. She had uncovered the letter from Henry Pickering to Iris explaining the Mercurius machine."

"Yes, which has only been read by myself, Rachel, Martin Richards and Iris as far as we know."

"Rachel had some communication with Martin Richards through the society. When she went to speak to him, she found Martin Richards' body and realised that Mercurius had been stolen. And, somehow, during that time, she became involved enough in the aftermath of Martin Richards' murder and the evidence that was planted there, that she joined O'Neill's task force as a CI. For information, but also for her own protection."

"And then, at some point following Martin Richards' murder, Rachel spoke to somebody outside the investigation about Mercurius. And that person either killed her, or ordered her murder."

Jane nodded. "And our best guess at the moment is that Kaplowitz knows who the killer is."

"So where do you propose we start?" Maura asked, overwhelmed by the sheer volume of information scattered on the table.

"We need to find him."