Romana found the Doctor in an unusually bad mood as he obsessed over the lack of doughnuts aboard the TARDIS. She humoured him and suggested he try the food machine, but he said machines are incapable of the panache and élan needed for cookery. He was fed up of eating healthily and said it was sometimes good to eat something that was bad for you. He’d tried asking K9 to make some for him, but he always used the wrong kind of jam, but at least this explained why his servo-motors had been so sticky recently. The Doctor set the Randomiser and hoped they’d arrive somewhere where there were lots of doughnuts.

The TARDIS landed in a leafy, luxuriant garden with sculptured topiaries, statues and fountains. Although it didn’t look very doughnutty, the Doctor agreed to a quick mooch around. They followed a path leading to a country mansion in a neo-Georgian style which epitomised the corporate ideal of affluence and the Doctor and Romana both agreed it was a bit gauche. They encountered a group of aliens jogging across the lawn, including humans, Morestrans, a couple of Sheltanaks and a species with leopard skin they couldn‘t identify. They were all dressed in fluffy blue bathrobes and were all considerably overweight. Leading them was a cylindrical robot which barked out instructions, like a personal trainer. The Doctor wondered if they’d landed on a world of fitness fanatics, which suggested the only food here would be carrots and celery rather than doughnuts. If there was one thing the Doctor couldn’t stand, it was celery!

A rather fat woman with a rich plummy voice told them they were at the Vita Novus Health Spa. She wore the same fluffy blue bathrobe but with pink bunny slippers and a floral headscarf. Instead of jogging, she was digging in the garden and she soon unearthed a tin containing a dark brown chocolate cake that she’d hidden there earlier. The Doctor was delighted to meet her. She introduced herself as Sebella Bing and invited them all to share the cake with her. Romana suspected Sebella was once a very beautiful woman who’d tried in vain to hold back the passage of time, but despite this she remained utterly charming. She explained that Vita Novus was an exclusive health resort that was so expensive you needed to own half a planet just to look at the brochure. Many of her friends had tried it and they’d all come back as slim as breadsticks - and as they’d all been such crushing bores about it, she thought she’d give it a try too. She soon realised she was fighting a losing battle so she’d smuggled in a cake, but she warned them the people who run the resort had eyes and ears everywhere and could see everything!

Suddenly an electronic trainer robot appeared and ordered them not to move. It had detected an illicit supply of cocoa-derived substances and Sebella reluctantly handed over the empty cake tin. She apologised for her moment of weakness, but the robot ordered her immediately to go to a treadmill to reduce her calorific intake. As she was jogged back to the mansion, she promised to catch up with the Doctor, Romana and K9 later. The Doctor noted that the name ’Vita Novus’ meant ’new life’ and he was starting to think there was something odd about this place. Romana felt she was being watched and realised the statues probably contained cameras and listening devices. They decided to investigate and the Doctor told Romana the bill wouldn’t be a problem as he already owned whole solar systems and once won the Arcturan Outer Cluster in a game of inter-dimensional Buckaroo.

Inside the foyer, Romana was overcome by the scent of mountain pine. Despite this, and the potted plants, the jewelled mosaics, marbled frescos, gold pipes and beautiful water features, the place felt curiously sterile. Romana felt uneasy that someone had gone to so much trouble and spent so much money trying to put her at ease. They tried to blend in with the other new arrivals, but it was obviously they were the only people there who weren’t dangerously obese. The Doctor decided they deserved to put their feet up for a bit and had gone off the idea of spending their time here investigating.

An extremely tall, thin and orange woman wearing a swirling white gown and diamond earrings arrived and welcomed the new guests. As proprietor of this establishment, Dame Montserrat Karna was proud of Vita Novus’s 100% success rate and she guaranteed everyone would leave thinner, fitter and happier after only a few days. No matter how self-indulgent people had been in the past, they’d leave here feeling like an entirely new person. Although she accepted that beauty is only skin deep and it’s what’s inside that counts, she said that’s no help if your skin is 20 inches thick and no one can make out what’s inside. She said everyone here had the potential to be slim and become one of the ‘beautiful people’ The Doctor considered this to be arrant rot, but Karna pointed to the guests who were leaving and pointed out that they were all in perfect physical condition. The Doctor asked how it was achieved and for a moment, Karna’s expression was scathing before it returned to its well-rehearsed smile. She ignored the question and instead commented that Romana didn’t look like the typical ’inertially challenged’ candidate for weight-loss therapy. Believing the Doctor and Romana represented a publication and were here to do a feature on the facility, Karna decided to take them on a conducted tour…one of the ‘special’ tours that she’d done before…

Dame Karna led the Doctor, Romana and K9 down a series of corridors, passing numerous alien guests engaged in various forms of exercise, but never far from the all-pervasive aroma of pine. Karna explained that the exercises were merely an introductory stage as it was necessary for guests to lose any excess bodily fluids before the main process began. She took them to a wood-panelled waiting room which was empty apart from some padded chairs and a coffee table. Once they were alone, Romana discovered they’d been locked in. The Doctor set to work on the door with his sonic screwdriver while Romana flicked through some brochures filled with glowing testimonials and numerous before-and-after pictures. There seemed to be an endless list of previous guests at the Health Spa, including presidents, pop stars, philosophers, evolutionary biologists and even tired TV producers.

Romana turned to hammer on the door, but found it was already open. She staggered out and closed the door behind her, temporarily trapping one of the fronds of seaweed. Her rescuer was Sebella Bing, who’d come looking for her as she was worried something might have happened. Romana told her about the homicidal seaweed monster, but they were interrupted by the arrival of two floating Burndroids who declared them as unauthorised personnel. They ran for their lives, only to find more robots approaching from the opposite direction.

Romana opened the nearest door and they found themselves in a concrete stairwell, which was a surprising contrast to the opulence everywhere else. They listened as the Burndroids buzzed outside the door, then they gave up and left. Romana told Sebella that Karna had tried to kill her, which suggested she had a secret she was prepared to protect at any cost. As they moved down the stairs, Romana noticed the air was getting stuffier. They heard the rumble of underground machinery which Sebella assumed was air conditioning or the laundry.

They arrived in the basement, a vast chamber lit by flickering neon tubes. Immense gold-plated pipes twisted across the floor and steam burst out of vents next to huge cooling fans. A large computer bank flashed and whirred in the corner. Romana was hit by the stench of roasting meat and when she examined the drainage channels, she found they were caked with dried blood. Sebella fainted and when she woke up again, she swore she’d be going on a diet and in the future she’d only ever eat cucumber. They followed some cables that led to a series of upright sarcophagus-like caskets, each big enough to contain an extremely large human being. The walls inside them were padded with a honeycomb of spongey material and there were wrist and ankle clamps. Romana realised this must be the main process Karna mentioned earlier and it explained how the Health Spa makes people thin.

Out of the shadows, Karna emerged and congratulated Romana, then she and Sebella were grabbed by the metallic pincers of two Burndroids. Karna explained that she’d discovered the secret of rejuvenation and, thanks to her ground breaking tissue reduction technology, no one need ever be obese again. The subject would be placed in one of the slimming booths and their cellular body mass broken down, filtered, cleansed and processed, then ultimately regenerated in a revitalised form. This is why everyone always left Vita Novus - “new life” - feeling like an entirely new person! Karna added that during the process, all surplus material (the fat, the blubber, the cellulite and any infected or damaged tissue) was discarded, leaving a pure healthy person replenished and reborn. After disposing of anything contaminated, the rest was synthetically reconstituted into the Spa’s own exclusive line of beauty products.

Romana thought this was utterly abominable, but Karna preferred to regard it as recycling. She said the subjects of the weight-loss programme submitted themselves willingly and they were always delighted with the results. Romana knew it wasn’t enough to change people’s bodies so the Health Spa must also change people’s minds, giving them a healthy outlook on life. Karna said they re-motivated their customer’s cognitive priorities so they would spread the good news and drum up business. If the Spa was to expand, they’d need influential friends in high places. Romana said this was brainwashing and they were turning everyone into zombies with no personality or individuality and Sebella remembered how all her friends had become crushing bores after leaving here. Karna argued that people wanted to be attractive and confident, to be one of the ‘beautiful people‘. She said fat people were miserable because they couldn’t wear nice clothes or avoid being stared at, and they were also environmentally unfriendly because they were so slow and unwieldy. Romana said the answer was for people to eat properly and exercise, but Karna said fat people didn’t have any willpower. Sebella became angry and insisted she had a glandular problem, but Karna wasn’t interested in such excuses and said the problem was that chocolate tastes too nice.

Karna admitted she was overweight herself once and lived only for cream slices and black forest gateaux. Her weight ballooned to such an extent that she was in danger of being reclassified as a minor planet. She loathed herself, but then decided to do something about it. She invested the life insurance from her third husband (and the alimony from the fourth) into diet technology and now she didn’t have a single ounce of fat on her body. She believed she was perfection personified and Romana had to resist the temptation to point out that she was also bright orange.

Romana asked her about the people who didn’t want to be thin and Karna said that’s why she ensured her business had sympathetic ears in all the intergalactic governments. She had a vision and the Health Spa was merely the beginning. Soon there would be similar centres on every major planet, processing the entire population. For those who didn’t want to co-operate, they had the option of dying. Romana scoffed at Karna’s brave new world and dismissed it as mass slaughter. Karna decided Romana and Sebella were much too dangerous to live, but their deaths would have to look like accidents. She ordered the Burndroids to take Romana to the Whirlpoolarium and then she had an amusing idea about what to do with Sebella…

Romana remembered a trick she’d learned at school on Gallifrey that had got her out of hot water once before. If Dame Karna wanted her dead, then that’s what she’d get. Romana summoned her last reserves of energy and willed her hearts to stop beating.

The plan worked and Romana regained consciousness to find herself lying on a hospital trolley being wheeled through the corridors of the Health Spa by one of the robots. She took the opportunity to recover her strength while avoiding making any sudden movements, then she swung herself off the trolley and ducked behind a wall. She headed back down the corridor until she heard a piercing scream from Sebella. She came to an unmarked door and burst in - whereupon she found Sebella completely naked on a massage table at the mercy of one of the Burndroids who was brandishing a needle. Thanks to the judicial use of a bottle of massage oil, Romana overpowered the robot and (thankfully) located Sebella‘s bathrobe. It was at this moment that Sebella declared she had no intention of giving a tip when she left.

Sebella knew she didn’t exactly have an athletic physique and said she’d never make it out of the grounds before getting caught, but Romana told her she had no intention of leaving yet as it was up to them to stop Karna. Romana suspected the victims were brought down to the basement while they slept, so they’d wake up the next morning looking thinner, but none the wiser as to how it happened. They entered a lift and as it descended, Sebella told Romana she was finding the whole adventure quite exciting as nothing like this had ever happened to her before. She was impressed by how self-assured, clever and daring Romana was and she’d decided to take a leaf out of her book from now on. In fact, she couldn’t wait to get home and tell everyone her story as she’d be dining out on it for months! Romana admitted to Sebella that she was actually quite frightened, which Sebella didn’t find particularly reassuring.

They arrived at the basement and were relieved to find it was deserted. The caskets were all empty and the computer screens showed only static, which confirmed Romana’s theory that Karna only used the chamber during the hours of darkness. Sebella volunteered to stay by the door and keep a lookout while Romana began examining the micro-circuits inside the computer. The mechanism was sophisticated, but nothing she couldn’t handle. She asked Sebella if she’d changed her mind about being thin, but Sebella insisted Karna was wrong and that fat people weren’t always miserable, at least no more than anyone else. It’s just that thin people always looked at them with disgust and pity. She said being fat was part of who she was and she didn’t want to change that just because of what other people thought.

Romana was hoping to find a way to invert the focus range of the regeneration matrix without depolarising the vector generator. Just then, Karna arrived, accompanied by a robot and armed with a bulbous laser pistol. Sebella was pinned against the wall by a second robot and Karna ordered Romana away from the computer. Romana reminded Karna that she needed her death to look like an accident, but Karna said she’d discovered Romana doesn’t actually exist. She has no identity papers, no insurance and no one to notice if anything dreadful happened to her. The first Burndroid whizzed over and seized Romana’s arms, then Karna ordered it to throw her into the slimming booth.

Karna told Romana that the booth could not only remove fatty tissue, it could also remove whatever percentage of a person’s body weight she cared to choose. In Romana’s case, Karna had chosen 100% and soon there’d be nothing left of her at all, except for the various beauty products that would be reconstituted from her body. Karna boasted that she could make any number of products from Romana‘s fat - from face cream to hand lotion.

Suddenly the voice of the Doctor called out from the shadows. Karna turned to look at him, her face twisted in a snarl of anger, then the two robots zoomed across the room to intercept the Doctor and K9. Romana demanded to know where they’d been and K9 revealed that the Doctor had been engaged in commercial transactions in the souvenir facility. All this time and they’d been in the gift shop! The Doctor proudly displayed a large fluffy pink and blue towel and when he saw the look of horror on Romana’s face he said he should have realised she’d have preferred the scented bath salt gift basket. Romana quickly explained that Karna planned to get rid of all obese people, whether they liked it or nor, and the Doctor was appalled. Karna insisted she simply had high aesthetic standards and said there was nothing he could do to stop her, but the Doctor pointed out that although she may have been beautiful once, she now resembled a Satsuma. He said beauty is in the eye of the beholder and there's no point in being good looking if everyone is beautiful. Karna’s problem, he said, is that she didn’t have a beholder. She surrounded herself with robots and didn’t know what it was like to be adored or loved for who she was. If someone has to manufacture beauty, then it ceases to be beautiful because it’s been artificially created rather than a result of nature.

The Doctor asked Karna what she’d do once she got rid of all the fatties? Would she then turn her attention to ugly people, short people or people with the wrong coloured eyes? Karna said it would be worth anything to bring greater harmony to the galaxy and she believed people would thank her eventually as it was all for the greater good. The Doctor accused her of being scared of people who didn’t think the way she did and who didn’t live their lives the way she wanted them to.

Karna hit the switch on the computer and a powerful throbbing filled the air. On the Doctor’s orders, K9 opened fire on one of the robots and it exploded in a shower of sparks. The Doctor used his towel like a matador and distracted the second robot until it span erratically across the chamber then smashed into the computer, causing it to erupt into flames.

Karna screamed insanely and her eyes filled with tears of rage. Unfortunately for Romana and Sebella, the process had already begun and with the computer destroyed, there was no way to deactivate it. Romana called to the Doctor and he rushed over and tugged at the clamps holding her inside the casket. It wouldn’t work, so Romana told the Doctor to climb inside one of the slimming booths. She said she’d reversed the focus of the regeneration matrix, which meant everyone inside the booths would remain the same and only those outside would be altered. As the Doctor did as he was told, a terrible storm rose up from nowhere, breaking the pipes free from their moorings and causing the computer banks to topple over.

Karna stood malevolently in the middle of the chamber and screamed in fury, then as the truth dawned on her she raced over to one of the remaining slimming booths. But the force of the wind was already too great for her and she slipped onto the floor. She tried to crawl on her knees, but it was too late and Romana watched in horror as the slimming process started to take effect. Karna’s back arched and her hands clutched in agony, then her orange skin began to dissolve and break down into swirling motes of dust, which rapidly disappeared from sight. Then, as suddenly as it had started, the storm faded away to nothing. Sebella was in shock and asked what happened to Karna and the Doctor said she fulfilled her ambition and slimmed herself out of existence.