In a sumptuous mansion in Hampstead (a suburb of North London inhabited by a species that a scientist might call humanus richus), Amura, the fat white Siberian tigress, was surfing through fashion websites on her laptop. She was clicking with her mouse, buying more designer dresses, perfumes, shoes and handbags from the most expensive shops. All day and all night, new deliveries arrived at the mansion.

Amura’s owner was an eccentric Russian billionairess who loved to collect exotic animals. She kept the tiger in her luxurious London home, but, because the billionairess had houses all over the world, she rarely came to check on her pet tiger and Amura had taken over the mansion, treating it as her own palace, naming it Tiger Towers and spending her owner’s money on the internet.

In the grand master bedroom, Amura was surrounded by a trio of she-wolves, called tundra wolves. They had thick white fur, bright sapphire-blue eyes, sharply pointed ears and long noses that sloped up at the end. These wolves looked after Amura’s every need. They served her, pampered her and protected her and never complained, even though she was a very demanding tigress!

At this moment, one was painting liquid gold on to the claws of Amura’s right hind paw, while another served her favourite delicacy: deliciously light and fluffy powder-pink marshmallows, which she ate sprinkled with black caviar from the Caspian Sea. The third tundra wolf was unpacking the items that Amura had ordered on the internet, holding up new pairs of shoes, dresses and sunglasses for her boss to inspect.

‘Keep that! Send that back!’ Amura was saying as she viewed her shopping. While this was going on she was covered in thick bleaching foam, because Amura was actually a yellow tiger and had to dye her yellow fur white because she had watched a documentary on television about white tigers and thought they were much rarer and more glamorous than yellow ones. (At one point, she had wanted to be pink to match her marshmallows, but the tundra wolves had managed to talk her out of it.) Her hairdresser, a manicured lilac poodle who was owned by the proprietor of a beauty salon on the high street, was putting the lids on the tubes of dye she had stolen from the salon while she waited for the bleach to work its magic.

Now only Amura’s eyes were visible, blinking through two holes in the froth, and she was very pleased with her eyes, for they were a rare and beautiful green, the colour of pistachios. She did not need to dye them.

A string trio of blind moles had been hired to play disco music on electric bubblegum-pink violins, but Amura shushed them as her attention was drawn to the huge TV screen in the centre of the room. A newsflash was reporting that the famous Siberian Diamond had been stolen from Buckingham Palace. The reporter said that the police suspected that the Russian Secret Service had stolen it on behalf of the Kremlin, for the Russians had been demanding its return for the last one hundred years. But the Russians were denying they had anything to do with the theft and the President himself had sent a message of sympathy to the King and Queen, promising to do all he could to help find it.

However, Amura knew the police were wrong. Oh, how she revelled in their ignorance! She chewed her marshmallow and caviar and smacked her lips.

You see, the Russian Secret Service hadn’t stolen the diamond; she had. Well, to be more accurate, her three cunning tundra wolves had stolen it for her because Amura was much too lazy to sneak into Buckingham Palace. ‘Bring me the Siberian Diamond or I’ll eat you!’ she had told them.

Why did Amura want the diamond so badly, you may ask. Amura had plenty of jewels for she was rich, very rich, on account of having remembered all the numbers of her owner’s credit cards (Amura had a very good memory). But the trouble with rich people is that they can never be rich enough. They always want just a little bit more. There is always someone richer and they always want what that someone has, even if it’s the Queen!

In Tiger Towers, everything was white apart from the indoor swimming pool, which was black and decorated with a mosaic of a white tiger on the bottom. Amura filled the house with every kind of luxury. She had all that money could buy, but she had grown bored and dissatisfied, because material things do not bring lasting happiness. One grows tired of them very quickly and starts to feel empty and craving more. But Amura didn’t know this, which is why she decided she must have the Siberian Diamond, the most beautiful jewel of all, because it was one thing she couldn’t have (and greedy creatures like Amura always want what they can’t have). She had seen a photograph of it in a magazine while she was having her fur dyed and decided that, as it came from Siberia like she did, she really ought to own it. Only the Siberian Diamond could make her happy, she believed. But, so far, it had not made her as happy as she’d thought it would. Something was making her discontented, but she couldn’t think what it was.

When her nails had dried and her fur was the colour of snow, the hairdresser left and Amura wandered into her dressing room to decide what to wear. She took a long time flicking through the rails of hanging outfits. There were rows and rows of shelves, and cupboards full of clothes and shoes and handbags, and every item showed the label of the shop it had come from. Amura’s favourite shop was the ridiculously expensive Jazz Tiger, and most of her clothes displayed the JT logo in big gold letters for everyone to see. Even the towels in her bathrooms had huge JT logos emblazoned on them. Once she’d chosen her outfit, a shimmering metallic evening gown in the brightest silver, she wandered back into her bedroom.

At last, she stood in front of the magnificent Siberian Diamond, displayed in a shiny glass cabinet against the wall near her bed, so that when she woke up in the morning and went to sleep at night it was the first and last thing she saw.

The tigress rubbed her polished paws together and her chubby cheeks creased as she smiled. But her smile wasn’t as wide as it should have been. Her three tundra wolves stood beside her in tight black jumpsuits with gold belts around their waists, and gazed at the diamond they had stolen for their mistress.

‘It’s more beautiful than the moon,’ gushed Sapphire.

‘More beautiful than the sun,’ enthused Lapis.

‘More beautiful than the stars,’ exclaimed Topaz.

‘But less beautiful than me!’ purred Amura in a little cub voice, and she wasn’t joking.

‘Of course, Amura. Nothing in the world is more beautiful than you!’ the wolves replied in unison. They knew how to flatter their mistress.

Amura huffed and suddenly looked deeply unhappy. She popped a deliciously light and fluffy powder-pink marshmallow into her mouth. ‘I thought stealing the diamond would make me happy. But what good is it if no one knows I have it?’ she complained.

‘But Amura, if the Russian Secret Service know you have it, they will try to take it from you,’ said Sapphire sensibly.

‘If the British Secret Service know you have it, they will try to steal it back as well,’ warned Topaz.

‘But I want everyone to know how clever I am,’ Amura wheedled in a sulky voice.

The wolves glanced at each other nervously.

‘And I want everyone to know how rich I am. Now that I have the priceless Siberian Diamond, I am richer than everyone else in the whole wide world. But what’s the point if I can’t show it off?’

At last, she had reached the core of her discontentment. She would only be truly happy if everyone knew she had the diamond!

Now the wolves began to look really uneasy. When Amura wanted something, she usually got it. The something that Amura wanted now was not, they knew, a good idea. However, they were not paid to advise but to act upon her every wish, so, if Amura insisted, there would be nothing they could do to dissuade her – after all, they didn’t want to be eaten.

‘How about we make a deal with the Ratzis?’ Amura suggested, tossing another caviar-sprinkled marshmallow into her mouth.

Sapphire’s jaw fell open in horror. Lapis gasped and Topaz snarled, baring sharp white teeth. Normally, wolves are not afraid of rats; however, Ratzis, as I’m sure you know, are not ordinary rats: they are giant super-rats who work for the world’s biggest internet company run by the mysterious Papa Ratzi. ‘The Big Ratzi’, as he was also known, would have loved to learn that Amura had stolen the diamond so that he could publish the real story in his newspapers and prove everyone else wrong.

Sapphire thought of the greasy, smelly, junk-food-eating Ratzis and turned up her snout. ‘You can’t trust Ratzis, Amura.’

Amura smiled the sly, greedy smile of a tigress who is never satisfied. ‘But if I just let them know that I might have the diamond,’ she purred.

‘I’m not su—’ began Lapis.

‘WHAT IS THE POINT OF HAVING IT IF NO ONE KNOWS I’VE GOT IT!’ roared Amura. The wolves jumped in alarm, for when Amura roared, it was thunderous.

The Siberian tigress chewed another marshmallow and added, more softly, ‘The Russians might have it or I might have it, but no one will know for sure, will they?’ She turned to Lapis, her expression deadly serious. ‘Let’s give them a clue. Set up a meeting with a Ratzi. This is going to be fun!’

A short while later, in a damp alleyway in Central London, a fat, greasy rat with a jutting jaw and a dribbling loose lip (which was the result of a fight she had had with a vicious badger – and won) stood waiting for the mystery animal who had requested a meeting with her, promising a scoop.

Slippery Mavis was awful, even for a Ratzi. Her belly bulged from all the junk food she ate, her bottom let out terrible farts because of the fizzy drinks she drank and her breath was so stinky that flies died in mid-air if they flew within a few metres of her.

But Mavis was ambitious. She wanted Papa Ratzi to be pleased with her, because if he was he might reward her by making her famous. He might even give her her own reality TV show! After all, once, when a rat had pleased Papa Ratzi, he had granted her a wish. (That rat had only requested a holiday in the sewer – Mavis would ask for more, much more.) She craved fame more than anything in the world. She wanted to be a celebrity, and she’d do anything to be one.

If this scoop turned out to be a delicious scandal, Papa Ratzi would be very pleased with her indeed! So she waited in the rain, smartphone in one hand, tablet in the other, because while she had time to kill she might as well play a few games.

Suddenly, a lithe and agile creature bounded down the alleyway and came to an abrupt stop before her. It was dressed completely in black – black jumpsuit, black boots, black gloves and a black mask – and Slippery Mavis wasn’t even able to tell what sort of animal it was. But she could see that it was very tall and slim and powerful. Mavis did not want to get into a fight with this creature, whatever it was.

‘What have you got?’ Mavis asked as a drop of drool slipped from her lip and plopped on to the wet cobbles by her hind paws. The creature pulled an envelope out of its breast pocket. ‘What’s this?’ Mavis asked, snatching it out of the gloved paw. But, before Mavis had time to open the envelope and look inside, the mysterious creature had darted away, like a sprite into the darkness.

Slippery Mavis snarled furiously. There was no explanation. Not so much as a ‘hello’. Yet she was curious to see what was in the envelope. Better not look at it in the rain, she thought. I’ll wait until I get back to Rat Central. She put it in her rucksack, pulled out a rotten tuna sandwich she’d found in the park that afternoon and took a bite. The tuna was off and the bread was stale, just how she liked them. She licked her chops and made her way back to the Shard.