The tree had died in the bitter cold of winter, although no one would notice yet. The wouldn't notice until spring came around and the dry brown leaves weren't replaced with fresh green buds.

The chill of winter was still in the air, even though March was well underway and the sun was pleasantly bright in the sky. His shadow was full and dark on the asphalt outside UNIT Headquarters. The air ruffled through his hair and bit at the tops of his ears and he was once again glad that he had chosen to wear a heavy overcoat. The thick woollen material might weigh him down slightly but it kept him warm, and the pockets were pleasingly deep. Reaching down into one, he pulled out the small scrap of paper that had led him to come out this afternoon. It didn't say much, just "come alone and unarmed" with the time and location printed in girlish handwriting. There were little hearts over the I's and the letters themselves had an overall roundness he had noticed men never had.

"Are you unarmed?" came a voice from behind him. He smiled when he recognised it and turned round, a disarming grin on his face.

"Miss Grant," he said. "It's a pleasure to make your acquaintance again."

But the young UNIT operative wasn't falling for his charm. She pulled a small pistol from a shoulder holster and pointed it at his chest.

"There's a rifle pointed at you. If you make a move, you will be shot."

"Forgive me, Miss Grant, I did think this invitation was of some importance. If I had known you wished to kill me, well, I suspect that I wouldn't have come."

In truth he didn't believe that even if Sergeant Benton or whoever it was with the rifle pointed at his head - he couldn't see them from where he stood, they must be behind him - did get off a shot, it wouldn't kill him. Miss Grant was an entirely different proposition. She might not be a crack shot, but at this range it wouldn't matter. If the bullet were to rupture either of his hearts he would be in trouble. Subtley, so that she didn't even notice, disguising his movement with the raising of his hands in the "I surrender" gesture, he shifted to one side so that the bullet - if she did manage to get a shot off - would ricochet off his rib cage.

"I trust you can believe me when I tell you I am unarmed," he said. "You can search me if you like."

As if on cue, a UNIT private came into sight, a rifle clasped firmly between two sweating hands. He wouldn't be susceptible to hypnotism, the Master decided. No, Miss Grant might follow the fawning Doctor around and ask all manner of fool questions but when it came to common sense, she had her fair share.

The private frisked him, a process the Master found extremely embarrassing. He stopped at the Master's inside pocket a produced a small fob watch.

"It just tells the time," the Master assured him.

The private unhooked it and passed it to Miss Grant. Then he discovered the Master's Stattenheim remote control. It had it's own small chameleon circuit and was, at the moment, in the form of a fountain pen. The private popped the cap off it, looked at the nib. The master grimaced, he was probably thinking about how it could be deployed as a deadly weapon. Humans had no sense of style. The private gave the pen to Miss Grant, and, when she noticed his look said: "Don't worry, you'll get them back when we're done."

"Done with what?" the Master asked, finding his temper almost gone. There was some plan afoot and he didn't know what was going on. That infuriated him.

Miss Grant looked down at her feet. The Master followed her line of sight but didn't find what she found so interesting. Then her eyeline snapped back up. Her gaze met the Master's. He could tell that she was in no way comfortable with this situation.

"We need your help," Miss Grant said.

"That much I figured," the Master said sarcastically.

"The Doctor's been immobilised."

***

She hadn't been exaggerating, the Master mused when she led him in to the Doctor's laboratory. The Doctor lay on the floor, gazing up blankly into space.

The Master picked up the Doctor's hand. It was still flexible, there was no sign of muscular atrophy or rigor mortis. A few seconds later, holding his fingers to the Doctor's wrist, he registered a very faint double-pulse.

"He's still alive," the Master said, standing back up. He looked at Jo. "What did this?"

"I don't know," Jo said. She held her arms wide in front of her. "it was this big. Red. Blobby. Looked like one of Omega's Gel Guards."

"Omega?" The Master raised an expectant eyebrow.

"But it wasn't," Jo added quickly.

The Master turned back to the Doctor. Omega? The Stellar Engineer? The Doctor had been busy since Atlantis. "What was the Doctor doing before this creature immobilised him?"

"He was on about going to Metebilis 3," Jo said.

"A rather nice holiday spot," the Master mused. "Probably has nothing to do with this. I think perhaps Earth is facing another invasion." He turned to Jo. "You know, for such a small insignificant planet you don't attract many invading forces do you?"

Jo Grant didn't look too impressed with that joke, the Master mused, so he turned back to the Doctor, snapping his fingers in front of his eyes. "Pass me that pen-light, please Miss Grant."

Jo took the Doctor's slim torch from the workbench and passed it into the Master's gloved hand. He shone it in the Doctor's eyes. "As far as I can ascertain with this primitive equipment, he's simply paralysed." He looked at the Doctor's face and smiled. At last he didn't have to suffer his insufferable patronising tones.

"Will he be okay?"

"In time, Miss Grant. In time." The Master rose to his feet again and placed the torch back on the bench.

"Or rather right now," the Doctor said.

"Doctor!" Jo screamed excitedly. She dashed round the Master, skittering to her knees at the Doctor's side.

"I still appear to be mostly paralysed," the Doctor said. His mouth was barely moving. His eyes were darting about in his head. "Jo, why did you bring the Master? Lethbridge-Stewart will be most annoyed."

"Annoyed?" the Master mused with a smile. "I suspect he'll be more than that."

Jo looked sheepish.

"Jo?"

"I didn't tell him. There's only myself, Corporal Benton and a couple of Mike's officers who know," Jo admitted.

Even paralysed on the floor, the Doctor managed to give Jo a look of withering scorn. "Anyway, believe it or believe it not, Jo, bringing the Master here may well have been the best course of action." He turned to his former friend, now nemesis. "The creature that attacked me. It was a Chronogol."

The Master felt the colour involuntarily drain from his face. "A Chronogol?"

Jo looked between them. "What's a Chronogol?"

Before the Doctor cold reply, the Master uttered, "One of the greatest enemies of the Time Lords."

"They are the bastard offspring of the Chronovores, Jo," the Doctor said. "They, like them, devour time. As such, us Time Lords are very susceptible to their powers. They can literally suck the memories from you." The Doctor was flexing his fingers experimentally. "One of them disabled me when it invaded my mind and I set up a range of mental barriers."

Noting that Miss Grant seemed to be a little confused by this whole situation, the Master interjected. "Time Lords like ourselves who travel widely have to erect many barriers to protect ourselves from the ravages of time travel. Without them, our secrets, and those of the Time Lords, would be exploited by the first telepathic race we came across." The Master turned to the Doctor. "Was there just the whole creature?"

"Yes," the Doctor said. "And it's injured."

"Then we must find it and destroy it before it does too much damage," the Master said.

"Use my TARDIS. Take Jo," the Doctor said.

Jo looked aghast at the Doctor.

"It's the best thing, Jo. Keep an eye on him."

The Master scowled at the Doctor, but made his way across the laboratory to the small police box stored in one corner. Amidst all of the assorted junk the Doctor had collected from dozens of alien worlds, the TARDIS didn't look too far out of place.

Jo reluctantly handed him the key and he opened the door.

***

Inside the TARDIS, as Jo entered and closed the door behind her, the Master set to work straight away on the console.

"What're you doing?" Jo asked.

"Setting the time path indicator to back track over any chronon particle discharges that are out of place," the Master said without looking up.

"Huh?" was all Jo could say. All of this was way over her head.

Suddenly, the time rotor began shifting up and down and the Master turned to her. "What that all means, Miss Grant, is that we are following the Chronogol's feeding pattern."

Jo's nose involuntarily wrinkled. "Feeding pattern?"

"And, as it is injured, it is likely seeding the city with its blood, with is so rich in chronon particles - particles of time if you will. The TARDIS will be able to pick up on these as time moves at different rates. It'll be classified as a chronon-pocket"

The time rotor stopped moving.

"Where are we?" Jo asked.

"Let us see, shall we?" The Master opened the door and immediately the sounds of a terrified crowd flooded in. A smile spread across his face. "Piccadilly Circus," he said with a smile. "It appears our friend is already here."

"What are you going to do?" Jo asked, following the Master out of the TARDIS.

The Master removed his Tissue Compression Elimator from his pocket.

"How did you get that?" Jo asked, shocked. "We searched you."

"Obviously it appears you did not search hard enough." The Master looked across the street to the scene where the biggest disturbance seemed to be taking place. "We need to destroy this creature, Miss Grant. My TCE is simply the easiest and quickest way to accomplish this task."

The crowd seemed to part as the Master strode forward, revealing a person lying on the ground, the red blobby form of the Chronogol covering much of the man's body, blood red tendrils oozing into his head through empty eye sockets. Even though Jo had seen much death and suffering as part of her time at UNIT, she still wasn't used to it.

"Step back please," the Master said. "I am a police officer."

The crowd obeyed and went about their business. Jo caught the look in their eyes as they wandered off, an instantly recognisable blank stare. He had hypnotised them all.

"Don't worry Miss Grant," the Master said. "There will be no permanent effects. The hypnotism will wear off in time."

He held up his TCE and aimed it. The Chronogol seemed to be too busy feeding to notice. A small glow emerged from the end of the black stubby weapon. The Chronogol screamed in terror and pain and began to shrink, collapsing in on itself.

When it was silent and as small as it could be, the Master picked it up. "I had no idea that releasing Kronos would also release its offspring."

Jo thought he had said it so quietly that he thought she wouldn't hear, but she did.

"That's taken care of that." The Master turned to Jo. "Would you like me to take you back to UNIT Headquarters now?"

***

The Doctor was up and walking when they arrived back at UNIT HQ. The sun was setting now, behind the tree that the Master had first noticed when he had arrived.

"I'll be seeing you around," the Master said, smiling his charming smile. The Doctor smiled back, even though he didn't feel as if their next meeting would be overly pleasant. The Master strode out of the door.

Jo was silent.

"Something wrong, Jo?" the Doctor asked.

"He... he killed that creature. And the man it was feeding on."

The Doctor's brow furrowed. "Sometimes, Jo, it is necessary to kill. And the man the Chronogol was feeding on, he wasn't a man anymore. The Chronogol would have decimated his memories."

"No," Jo said. "He was still alive."

"He might have been breathing, Jo, but he wasn't alive."

Jo felt like punching something rather than just standing there, staring at the door which the Master had just walked out of, she felt so impotent and weak.

The Doctor laid a reassuring hand on her shoulder. "How about a trip to Metebilis 3?"

Jo looked out of the window. She noticed that the tree outside was still clinging to the dead brown leaves. It was dead. She closed her eyes for a moment, but still saw the Master standing over that poor man. Gazing up at the Doctor, she nodded.

He led her towards the TARDIS.