I know it's been a while, but this story did begin with a thread about a burrowing parasite that needed a good Doctor-style ass-kicking. We got distracted by the thing with the books... but now we return to the parasite. Just a heads-up. :-)

PART FOUR

Martha wrapped up her work and found the Doctor, approximately an hour later. He was busying himself in one of the laboratories, researching the chemical bombs they would need to dispatch the burrowing Nosaminta parasite.

"I've set aside a few pages that we can use to verify Borstel's hypothesis," she told him slowly moving closer to him.

"Good," he told her, eyeing her as she approached.

"I've chosen two different scenarios," she told him. "Couldn't decide between them."

"Okay, well... I'll leave that to you, I guess. Have you finished reading for the moment?"

"I have. And I am now ready to devote more time to you," she lilted, snaking her arms around his neck. Her skin touched his, briefly, and she was hot to the touch.

"What do you mean by that?" he asked, with a smirk.

Her entirely non-verbal response, over the next forty-five minutes or so, gave the Doctor a big clue as to what sort of texts she had chosen for them to test Borstel's theory. She had said originally that she had selected a self-contained story with only two characters, who never left the room... and now she was saying she had selected a second "scenario" which liked equally well. It didn't take a Time Lord to see what she meant.

And in fact, a bit later, when they, once again, lay side-by-side, sweaty, spent and breathless on the floor of yet another TARDIS facility not originally intended for such activities, he asked, "Goodness gracious, Miss Jones, what have you been reading?"

For the next few days, they concentrated on what they would need to do away with the Nosaminta and its stone-burrowing, structure-compromising, building-collapsing ways. They spent hours mixing chemicals, examining the molecules and experimenting with different cocktails. They needed something that would kill the parasite, but not harm anyone else in the opera house.

They also focused some attention on their costumes, since they had decided that the best way to get close to the Nosaminta's hiding place was to go to the commemorative fancy dress ball. They had delved into a few of the TARDIS' costume warehouses and searched for the perfect thing that would let them blend in on the planet Dionumah. They needed something culturally appropriate, relatively innocuous yet clearly a costume, and properly sized.

The Doctor selected a black suit which had come originally from a planet that neighboured Dionumah. It was the formidable uniform of a constable; a straight, tunic-like jacket with eight cloth-covered buttons, capped by a grey straight collar, and finished with a pair of carefully-creased trousers. The Doctor favoured a snug-fitting garment, and anyway, he had been a bulkier man when he had acquired the uniform, so he set about altering it to suit his current, rather thin, frame. The uniform had not come with a mask, so he had retrieved a gold Mardi Gras mask from the depths of one of his bedroom drawers. He tried it on, and it fit well, so he left it on the night stand until ready to wear.

Martha decided on a butterfly costume, which the Doctor said had probably come from Earth, but he could not remember who had worn it or why. Whoever it was, she had been an inch or two shorter than Martha, because the lavender-coloured tulle skirt hit her well above the knees, and she reckoned it was made to fit longer. The strapless bodice, though, was like a corset, fitting taught and flattering her thin waist and curvy hips, pushing her breasts up toward her chin. It was made of some kind of iridescent lavender fabric, and capped off at the bustline with silvery, feathery embellishments. The same embellishments also lined the bottom of the bodice and the v-shaped rift in the back where the garment laced up.

The butterfly's wings were huge, about three feet long, and attached to the laces in the back. They were made of shiny lavender and royal purple silken netting and lined with the silvery embellishments, sporting diamond-like rhinestones in a spiral pattern. Martha took a dive into another costume warehouse to find appropriate shoes. A pair of high-heeled silver sandals caught her eye, and when she tried them on, she was very impressed with what they did for her height and the shape and colour of her legs.

The butterfly costume had come with a mask, but she had discarded it and left it in the warehouse.

She did not have any need to alter the outfit, so she hung it in the bedroom until the ball. So, while the Doctor was altering his clothing, she locked herself in one of the workshops and coyly refused to say what she was doing.

When the night finally arrived, they packaged and calibrated the chemical bombs and put them in the console room, ready to go. Then, the Doctor and Martha retired to dress in separate quarters - she in the workshop, he in one of the labs, and they met up in the bedroom to admire one another.

The Doctor was more than a little taken aback by her costume. He had seen it before, but only on the hanger (as far as he could remember, anyway) and had not anticipated the difference it would make once she was in it. He found her breathtakingly beautiful even on her worst day, and he appreciated every inch of her, but...

...well, he felt almost ashamed of the effect of the high heels and cleavage. Suddenly his no-nonsense, comfortably lovely and sometimes demure companion was a bombshell with sinewy golden brown legs that seemed to go on forever, and a formidable rounded bust.

"Wow," he said, his throat going dry.

"Yeah?"

Gulping, he answered, "Yeah."

"Thanks." Then, she seemed to look him over for the first time, and she blushed, and looked away.

He smiled. "Why are you blushing?"

"I went to Catholic school," she replied, returning his smile. "And I'm not supposed to have these feelings."

He turned and looked at himself in the mirror once more. "I suppose I do look a little like a priest," he commented. Then his voice switched to mock-earnestness. "But I am, in fact, a constable."

"Yes," she sighed, once again looking him over. "Which brings me to my little surprise."

"Another surprise?" he asked.

"I have this for you," she said, reaching into a little canvas bag she had brought with her from the workshop. She produced a black and white mask and held it reverently in both hands for the Doctor to take. He picked it up gingerly and examined it.

"Papier mâché?" he asked.

"Mm-hm," she answered.

"Did you paint it yourself?"

"Mm-hm," she repeated.

He ran his fingers gently over the beautiful swirling pattern, reminiscent of a large paisley.

"Well, you are a talented woman! And this is so much better than that gold Mardi Gras rubbish," he told her, pulling the elastic band back and fitting the mask over his head and eyes. It fit perfectly around his eyes, extending down the sides like legs to cover part of his cheeks, but leaving just enough room for his mouth and nose.

"I agree," she said, admiring her work.

"And it fits!"

"I used the gold Mardi Gras rubbish as a model," she told him. "You said it fit, so I reckoned..."

"It's brilliant, Martha."

"Thank you," she chirped. She produced another mask from the bag, identical except the paisley pattern was painted in lavender and royal purple. She fitted it over her face, and asked, "Now, what do you think of this one?"

"I love it," he said with a smile. She could see him smiling, but marvelled at how much of his wonderful face, and its expressive nuances, were obscured now.

"Shall we be off, then?" she asked, gesturing grandly toward the bedroom door.

He sighed. "I'd much prefer to stay here and enjoy that costume properly," he told her, taking her in again with his greedy, masked eyes.

"Sssh," she lulled. "Hold that thought."