"So what should we expect?" the Doctor asked, "How should the corpse look like?"

"A man in his thirties," Vastra answered as she pushed open the iron gate of the cemetery that Jenny had forced. "Blond hair, not too long. With a muscular frame and average height."

The Doctor picked up a shovel when he saw one near a grave, as Vastra lead them to the murderer's tomb.

It was a mass grave. Both the Doctor and Vastra covered their faces with handkerchiefs, the smell of death impregnated the air and they were much more sensitive than a human, whereas Jenny had grown up in one of the most miserable areas of London and was somewhat used to the least pleasurable smells.

"Well, the sooner, the better," the Doctor stated, handing Vastra the shovel.

"You're not expecting me to dig, are you?" the Silurian protested.

"Your pleasure, then, Jenny."

The human made a face and reluctantly grabbed the tool, gazing at Vastra hoping for some help.

"Sorry, my dear Jenny. This is why we usually have Strax with us."

It appeared clear to the human that, without the Sontaran, she was the lowest in the 'social scale': Gallifreyan, Silurian, human, potato dwarf. It seemed perfectly understandable. She was obedient and used to pretty much every 'dirty work', so she started to dig, but she inwardly cursed Time Lords, Silurians, their silly pride and their ideas about superior and inferior species.

Many minutes and a long excavation later, the Doctor lowered himself and looked more closely at the ground beneath.

"It's clearly been made some room for another body…which is missing," he noted.

"And none of these men has blond hair," Jenny pointed out. The bodies were dirty, and not in the best conditions, but it was evident that they all had very dark hair.

"What do you make of that, Doctor?" Vastra asked.

"Our man has been buried, but it appears that he… escaped."

"You mean he came back to life?" Jenny questioned, stunned.

"Oh, don't be silly."

"But how could he survive hanging?"

"In many ways. It's not such a precise method to kill someone, you know. A badly-knotted rope, the wrong position of the neck, and you'll be perfectly fine. You've certainly noticed before that not every single hanging is successful. That's why a doctor always checks if the person is effectively dead…" -he paused, as if realizing something, then continued with a lower voice: "…by assuring that he's not still breathing." He smirked contently.

"What, do you have the solution, Doctor?" Vastra asked.

"Of course I do," he said proudly. "We aren't looking for a human. We are dealing with an alien capable of holding his breath for a long time, so he's been able to hide in the tomb for several hours without suffocating."

"Is that even possible?" Jenny asked.

"Oh, yes, it's quite common in fact. Ilorians, Kradators and many others, even Time Lords have this ability. In my case, it's called respiratory bypass system. The alien we are looking for probably hid his real appearance in some way, maybe a strong perception filter… humans are easily fooled by perception filters. I'll have to return to the TARDIS and run a scansion for alien technology."

"I suggest we pass through Croydon, hoping to meet this creature," Vastra proposed.

"Yes, good point. We'll do exactly that."

~oOo~

When Clara found the gate of the cemetery open, she knew that she was succeeding in her intent to find the Doctor. At least it was very probable that he had been there.

All her remaining doubts faded as she saw three familiar figures step towards her in the dark. She would always recognise the Doctor, at night-time or in the daylight, no matter the face. His blue eyes were bright in the darkness, but Clara saw them darken as he met her gaze.

The Doctor had an extraordinary brain, but not even he could count the emotions that he experienced in the millisecond after he saw his companion walk towards him. There was happiness, as she always melted his heart when he saw her; he was worried that something could have happened to her and then relieved as he verified that she was fine; he marvelled that she had easily tricked Strax and then realized that there was nothing surprising; there was admiration for her, her bravery and cleverness. These and many other emotions were in his hearts, but the one that overcame all the others was anger, because she had disobeyed him and took unnecessary risks.

He swallowed, mouth dry, trying to keep calm. His hands were closed in fists, nails digging in his flesh.

"Why?" he asked simply, when Clara arrived close to him.

"Because I'm not letting you do everything on your own."

"I'm not a kid. I don't need anyone."

His sharp words hurt Clara, more than she would admit, but she wouldn't give up now. She had disobeyed him and taken a decision. Now there was no going back.

"I'm not a kid either. I don't care if you won't admit it, but you need someone. I'm not going to just sit here doing nothing when you go around risking your life. If you want me to be your companion, you will have to keep me always, both in the happy moments and in the dangerous ones. If you don't agree, then…" -she had to search very deep inside her for the bravery to pronounce the last words- "…then just take me home and leave and don't come back."

Clara shuddered. Had she really said that? With him, she never knew…would he take her home? She had just taken a dangerous step.

He stared at her, eyes wide. His gaze met hers again, and he could see determination but also fear. Clara couldn't read those blue-grey pools, as always. He seemed shocked and worried, but she couldn't tell.

"Can you promise me something, Clara?" he asked suddenly.

He, talking about promises. The one who lied so often.

"What?"

The Doctor stepped closer to her and took her hand in his.

"I have no desire to leave you, but I want you safe, Clara. Do you understand?" -he didn't let her answer- "Don't you dare leave my hand ever again, don't you dare leave my side and we can keep travelling together."

Clara didn't really understand. It seemed exactly what she had asked. She smiled.

"Okay, I promise."

"I'm serious, Clara."

He was selfish. He simply wanted to be reassured, so he could have a good excuse to always keep her close, so he wouldn't feel forced to leave her behind. He was trying to persuade himself that if they were careful, if she stayed with him and they weren't separated, everything would be fine.

"Okay," she said, squeezing his hand. He squeezed back, and didn't loosen the grip when he gave a nod to Vastra and the four of them started to walk, out of the graveyard and heading to Croydon.

~oOo~

"Look! It's him!" Vastra recognised the criminal immediately as she saw him in the dark alley. There he stood, looking down at a body that was lying on the street.

The Silurian had spoken in a low voice, but the alien apparently had a very good hearing, because he turned suddenly, facing them. The darkness hid the features of his face, apart from the hair, fair under the moonlight. As he realized that he was being chased, he started to run.

The Doctor, Clara, Vastra and Jenny ran after him, briefly stopping to check the body on the street: a man in his early forties, with blond but slightly greying hair, an old scar on his face. They had arrived too late, because he was already dead. Strangled.

The four ran after the murderer, but he was surprisingly fast and thanks to his head start hey couldn't reach him, despite their efforts. Suddenly, he entered a warehouse and locked the door behind him.

While the Doctor searched for his screwdriver, the four of them heard a strange noise from the inside, and when finally the Time Lord opened the door… nothing. The man they were chasing had vanished. There was no sign of him. They checked for other doors, but there weren't any. He seemed to have dissolved into thin air.

The Doctor frowned. He had only got a glimpse of his face, but he would swear he had already met that man. He was completely sure, but something didn't allow him to remember. The alien was undoubtedly using a very strong perception filter. No matter how much the Gallifreyan concentrated, he couldn't clearly recall that face in his mind.

Deciding to leave that problem for later, he scanned the room with his sonic, focusing on how the alien had escaped. The results make his eyes widen and his eyebrows raise impossibly, and Clara immediately noticed it.

"What's the problem Doctor?"

"I know how our friend escaped. He travelled in time."

"What?" Vastra, Jenny and Clara asked, simultaneously.

"Time travel leaves traces. And the sonic found them."

His mind wasn't focused. He kept having the feeling that he was missing something… there was a smell in the air… he should recognise it, he knew that he should. But he didn't. He decided that hated perception filters. He had never seen such a strong one, he had to admit. Only a few would be able to create one like it.

"What do we do now, Doctor?" Vastra asked.

"There's nothing we can do. The TARDIS is too far, I won't be able to get there in time to track the other time machine."

"But who possesses that kind of technology?" the Silurian questioned.

"Not many. But anyone could steal it. Clara and I will leave… contact me if anything new happens, but avoid conference calls, I hate them." He didn't like others to decide when he had to sleep.

The Doctor was cross, and worried. He felt something wrong, something approaching. Still far, but it was there: some great change that he didn't quite feel ready to face.