Di Greg Lestrade had seen many things in the course of his career, and being Sherlock Holmes' handler had caused him to see even more than he would have otherwise.

He was used to leaving his office at a moment's notice when Sherlock needed him; he was used to going for a drink with John when the doctor needed a break. Since the consulting detective had returned, he was used to spending evenings at 221B, sometimes joining in their bickering and sometimes content to watch.

And he was used to meeting Mycroft Holmes now and then. After Sherlock had disappeared – and everyone, including the British Government, had thought he was dead – somehow it had become a ritual for him to stop by at the Diogenes Club at his way home to keep Mycroft company over a glass of brandy. Maybe because no one else had spared Sherlock's brother a thought; maybe because John had more and more withdrawn into himself ; maybe because he had missed the annoying sod so much.

Whatever the reason, he and Mycroft had formed a sort of friendship, and it wasn't unusual that the British Government called him under the pretence of talking about Sherlock when he only wanted to ask if Greg would be going to the Diogenes Club that night.

So he wasn't concerned when Mycroft's name showed up on his phone display, or at least not as concerned as he had been in the beginning.

Which changed once he heard what he had to tell him.

"Sherlock and John have disappeared."

"What do you mean, disappeared?" he stammered, standing up and moving towards his office door without realizing he was doing it.

He knew Mycroft well enough to be certain he wouldn't use the word lightly. The surveillance the British Government had on his brother was perfect – or at least it was rare that Mycroft couldn't say where Sherlock was or was likely to be. But "disappeared" implied that he had no idea. "Disappeared" implied that Sherlock and John were God knew where, most likely in trouble.

"They were investigating a case" Mycroft answered, and from the slight reluctance in his tone Greg knew that they had once more been forced by him to do so.

"They never returned home."

"When did they leave the flat?" he inquired, glancing at his watch.

10 am. It was 10 am. He had seen them last at eleven pm last night, when he'd said his goodbyes and returned home.

This meant there was a chance they had been missing for nearly eleven hours. Too long. Greg was aware what could happen in such a space of time.

"At 2 pm. They arrived at their destination half an hour later. After that, there is no trace of them to be found".

Greg inwardly cursed Mycroft's discretion. He would need a better clue than "their destination" if he was to find them. And he would. He had to.

"Where were they?" he demanded briskly. He had no time to be polite. Mycroft had called him for a reason, and he had to get all information he needed as quickly as possible.

"There is a car waiting for you outside" the elder Holmes replied and hung up.

Greg sighed; he would have preferred to be told where he was going. But at least he would be going where they'd been before they had disappeared.

He barely took the time to bark at Donovan that he was leaving – she didn't protest, probably assuming it had to do with Sherlock. She hadn't complained once about their work with the consulting detective since he'd returned from the dead, and Greg had never been more thankful for this than at this moment.

He was disappointed to find that no one was waiting for him in the car. While had hadn't expected to see Mycroft, he'd hoped his PA formerly known as Anthea whose current name he hadn't bothered to remember would be there to tell him what he needed to know.

He tried to guess where they were driving, but he didn't know London as well as Sherlock.

He kept wondering what could have happened, even though it was useless. The situation was highly alarming. Despite ignoring what they were up to most of the time, Mycroft always knew where his brother and his blogger were. And if he didn't, he usually found them again within minutes.

And apparently he'd been looking since half past two in the morning. And he hadn't found them.

Greg forced himself to focus on the matter at hand, rather than his anger that he hadn't been contacted sooner. There was no reason to think that Mycroft would regard him as anything different than a last resort. Mycroft wasn't Sherlock, who had proven on more than one occasion that Greg meant more to him than his treatment of the DI would suggest, and who had pretended to jump of that roof not only to save John, but Mrs. Hudson and Greg as well, as he'd admitted not long ago.

Greg swallowed. He refused to live in a world where Sherlock didn't exist again. He would find them.

At least they were together. If one of them was out there alone, unconscious or not, kidnapped or not, Mycroft would have found him. They had to be together. They could look out for each other.

The car came to a halt. Greg looked out of the window and saw a big, non-descript building. He quickly opened the door, to the driver's surprise; apparently he had just come to open it for him, and searched for a street sign.

He recognized the name. They were in a part of town where he wouldn't have been able to afford a flat.

"Mr. Holmes is waiting for you inside, Sir" the driver interrupted his thoughts, sounding nervous, and Greg realized that Mycroft must have ordered that he be brought her as quickly as possible.

He smiled to reassure the man and followed him through the glass doors of the building.

If Greg wasn't already concerned, he certainly would have been now.

Mycroft was standing in the lobby, Anthea next to him.

Not many people would have been able to read the British Government, but Greg saw the worry in his eyes.

"Tell me everything" he said instead of a greeting. Normally, Mycroft would have raised an eyebrow, said "Good morning" and expected him to answer in a similar fashion, but he didn't, and it was another indicator for how serious the situation was.

"This" he raised his right hand and indicated the building with his umbrella "is a top-secret research facility."

He didn't bother to add that Greg wasn't to ever mention its existence to anyone. He knew the DI too well to think it necessary.

"Sherlock and John were investigating some strange incidents involving persons who had been paid by the head scientist for unknown services, and who showed up on the streets disorientated and unable to say what had happened to them."

"Why didn't you simply interview the scientist?"

Mycroft didn't answer and Greg sighed. The man was the head scientist of a secret lab, he had to have connections. Mycroft needed proof if he wanted to go against him, and Sherlock and John had been trying to find said proof.

"But if he gave them money – " he said anyway.

"The existence of the payments wasn't considered good enough evidence" Mycroft answered with contempt in his voice.

Greg didn't know who'd been protecting the scientist, but he was certain they would soon find themselves regretting it.

"Sherlock and John – "

"Entered the lab at half-past two" Mycroft finished. He didn't have to add that they had broken in.

"The scientist – "

"Doctor Trevelyan has disappeared as well".

It was the first time the man's name had been mentioned, and Greg wasn't surprised that he'd never heard it before. Whatever he had been researching, it wasn't supposed to be known.

"You are looking for him?" he asked, although he already knew the answer. Protected or not, Mycroft Holmes' brother had disappeared, and he wouldn't allow the suspect to escape.

Mycroft was silent, Greg was growing impatient. He had to do something, not stand here and theorize.

"So what do we know?"

"We know they entered the building" Mycroft answered. He shot Anthea a glance. She shook her head without looking up from her phone. Sherlock and John hadn't shown up anywhere.

"Sherlock would want to search the biggest lab" Greg stated.

Mycroft nodded, turned around and led the way.

The DI followed him, wondering where Sherlock and John could be – where they could have been brought. It would not be easy to capture them both.

"Any evidence of a struggle?"

"No. There is no evidence they were here".

Mycroft kept his voice smooth as always, but there was a hint of fear that Greg picked up, and it caused him to almost feel panicked.

That the British Government hadn't found any trace of them, not even in the place where they were known to have been last, was not good.

The lab was big and airy. And, as Mycroft had indicated, there was no sign of a struggle.

Greg could only look around and wonder why he wasn't out there, searching for them. The answer was obvious, of course; they didn't know where they should be looking.

"What was he working on?" he eventually asked. They could investigate Trevelyan. Sherlock and John had been after him, and maybe it would offer them a clue.

Mycroft led him to the scientist's office without a word.

Greg took a look at the files that were laid out on the desk. Either Trevelyan didn't like computers, or he was confident that he would be protected by whoever had helped him gain the position he held in the first place. He was not concealing what he was researching, only how he was doing it – Greg found out by reading the little he could understand.

It wasn't much, but it helped him form a theory that was so crazy that he turned to Mycroft and asked, "Trevelyan has been trying to find a way into parallel universes?"