He would not be cowed, though. ‘Tough’ was not his conception of a good politician. He knew – for the comments had been leaked to the press – what the party’s candidate thought of him: ‘He won’t see the blows coming, he’ll get taken apart.’ To this provocation, dignified silence had been his sole response. Careless of the threats and warnings, he had continued conferring with potential allies all through the summer months. His eventual campaign launch, from a café-bistro in the fourteenth arrondissement, had attracted photographers and reporters and a scrum of cameramen.

A lyrical, impassioned Cédric addressed the packed room. ‘Building teams to solve complex problems has been my life’s work,’ he noted, ‘even before I entered politics.’ He promised to put technology, science and knowledge at the heart of his campaign. He would fight for a Paris unbeholden to financial speculators; a greener Paris in which it was possible to breathe. A Paris in which distance from the city centre no longer enclaved entire districts.

He would always put Paris before his party, he said.

After ten minutes came the moment everyone who had managed to squeeze inside the café had been waiting for. Cédric’s overexcited voice almost ran away from him as he cried out, ‘I announce to you on this fourth of September that I have decided to run for mayor.’ At these closing words his face, so animated only seconds before, went blank with bewilderment. He gazed in astonishment at the joyous tumult he had just unleashed.

‘Vill-a-ni!’ chanted the crowd. ‘Pa-ris! Vill-a-ni! Pa-ris!’

It was not long past seven o’clock in the evening and every news channel in the country carried the launch live. The candidate’s voice and delivery and the confused look of wonder on his face went instantly viral.

As he stepped aside from the podium, the crowd swirled around him in a confused melee, tugging his sleeves and almost spilling him out into the street. He had made it outside when his spider brooch was swept from his lapel and had to be recovered from beneath the trampling shoes.

The brooches Cédric wore now on the campaign trail were smaller than some of his other spiders, and had less pizzazz than those decorated with brightly coloured beads. On the advice of his team, he also tucked his cravat, often a folded blue one, neatly inside his suit; while some days the cravat vanished altogether, to leave his collar open. In a further concession to respectability, his long hair and old-world beard, the latter cultivated since he had become a deputy, both received a trim. The result of these adjustments was a greater focus (or so it was hoped) on what the candidate said, at the expense of a style which had long made his reputation for eccentricity. It was hoped that when Paris’s voters saw him on TV or in the flesh they would see a plausible future mayor instead of ‘Cédric the Eccentric’ or ‘Spider Man’ as he had occasionally been dubbed.

But for these – rather modest – adjustments to his clothes and hair Cédric did not change. He never had any bad words for anyone. Not even for the party’s designated candidate, who could be snide and abrasive and with whom no reconciliation proved possible. ‘My door is always open,’ the apparatchik said coldly when reporters broached Cédric’s independent run. ‘I offer him the hand of friendship.’

The pudgy man’s hands were one reason why Cédric felt no animosity towards him. The fingernails, Cédric had noticed when the men met behind closed doors to air their differences, though clean and pink were thoroughly chewed.

Cédric recognised the nervous habit from his own boyhood, except that the object of Cédric’s chewing had been a sweater he wore in primary school. His sweater had been the record of his mute perplexity during lessons: hole after hole in the wool where he’d gathered up the collar between his teeth and nibbled anxiously. The confusing shifts between subjects, the pressure to keep up and still, the unspoken rules that no teacher cared to explain and that could land you in the naughty corner – all these served to deepen his already shy and solitary nature. As the other children spoke and sang in class, the wool’s ticklish taste in his mouth had been strangely comforting. He’d let countless right answers go unpronounced that way, his arm too rigid with nerves to raise it, the distance between his brain and tongue seeming infinitely long.

Cédric’s private talks with his rival were as short as each man’s team had expected. Far longer, if no more satisfying, were some of the brainstorming sessions at his campaign HQ. It was a feature of politics he didn’t relish, the exhaustive discussions of tactics with his advisors; everyone’s energies, he could not help thinking, would be so much better spent developing policy instead of trying to get one over on the other parties. Moreover, these conclaves had an unpleasant tendency to drag.

Back when Cédric had directed the capital’s mathematics research institute there had been plenty such powwows in his office. But he had never permitted them to overrun. A small sandglass flipped at each turn encouraged the participants to cut to the chase. From time to time, whenever he listened with one ear, he found his mind drawn to the constant motion of the whispery sand, the grains’ obedient journeys, so unlike the freewheeling molecules in a gas.

The polls were rather promising. They showed Cédric and the party’s nominee in a statistical tie – each on 15–17 per cent – within a few points of the sitting mayor, Anne Hidalgo, who was on 24 per cent. Crunching these numbers, Cédric’s team felt confident that the mayor’s lead over him could be closed.

‘Voters like you,’ they told Cédric. ‘They like you very much. But we have to bear in mind that popularity doesn’t always translate into votes. So we have to get you out there, show that you understand people’s everyday issues. Campaign stops in schools and shops and hospitals are all well and good, but we also need you hitting the pavement.’

Cédric nodded in assent. An open-air market was chosen to take him to one morning the following week. Those who flanked him, ready to hand out campaign leaflets, felt on edge; in such a setting anything could happen. What if their candidate made a fool of himself? It was one thing knowing how to give a good speech or lecture, quite another to talk to the average voter in the street.

Some of the buyers in the market pulled back when they saw Cédric approach, not wanting to feel dull in the face of his brilliance. They were men and women who had left school without academic qualifications, unable to make head or tail of algebra and geometry and all the rest of that airy-fairy business, and the feeling of shame or inferiority clung to them even after all these years.

But when they heard their aspiring mayor respond warmly to a fishmonger’s bonjour, all nerves went from them. He did not sound or look one bit like a politician, he had that much going for him. And he didn’t sound like a mathematician either, they thought, not that they knew what a mathematician sounded like.

‘How old is he?’ an onlooker asked her friend. ‘He has such a young face.’

The other woman googled him on her phone. ‘Forty-six.’

‘No! Where do you get that from?’

‘Wikipedia.’

‘Ah, well, if Wikipedia says so,’ snorted the woman.

But it was true. And the woman was quite right – the candidate did not look his age.

Other phones climbed out of pockets, filmed the scene, inched closer. And alongside them, shoppers with their baskets and grocery bags, curious tourists, the murmur of a small crowd.

Cédric posed for picture takers, let them snap away. They photographed his good side, his bad side. They photographed him reaching over a fruit stall; meeting a vigorous handshake; listening to someone’s overlong question. They photographed the suit and the spider and the concentration that was written in capital letters on his face.

The long question concerned housing. ‘Rent’s crazy here,’ the middle-aged man complained. Cédric nodded; he did not interrupt. And when at last the questioner relented, he replied thoughtfully. He insulted nobody’s intelligence. He did not pretend to have all the answers. He addressed the have-nots just as he did the haves.

People at other markets, on other mornings, brought all sorts of questions to him, on low salaries and dirty pavements, street muggings and trains that never arrived on time, and not one did he duck. His gaze, as he spoke, could be disconcerting – so intense and direct.

He was being himself, transparent and candid to a fault. And that was perhaps the problem. Many voters, though they told themselves otherwise, did not expect candour in their candidates. They did not want to hear things told straight. They wanted things told slant, the better to conform to their desires and preconceptions. A good politician should be all things to everyone – that was the gist of what they thought.

Could the buyers and sellers at these markets see themselves voting for him? He wasn’t cut out for politics, some said, he should have stuck to the maths; others affirmed that he had been courageous to pursue his candidacy. They debated whether or not he was telling truth to power, and, if so, which truth precisely was he telling it?

He might look funny and express himself funnily, thought a woman buying cheese, but at least he listens. He’s not like the rest of them.

‘’Course he’ll never win,’ a father said to his son. ‘Shame really. CV longer than my arm, prizes galore plus a Légion d’honneur. Cleverer than the other candidates put together.’

✲

The party pulled its punches with him, at least to begin with. How little they knew him to imagine that he would eventually tire and drop out. The dawning realisation that he wouldn’t, hit them hard. They began intriguing against him.

Towards the end of November, as he remained steady in the polls, Cédric was made aware of certain remarks about him that were circulating. Not only was he proper weird, it was being whispered, and completely out of his depth, he was borderline Asperger’s. He was autistic.

Paris’s voters deserved to know, was the implication. The mathematician’s backers were guilty of manipulating him; they were irresponsible. Poor thing, the gossipers sighed in mock concern. Crashing to defeat would be sure to bring on a nervous breakdown.

However, the butt of these rumours and innuendo did not anger. It was his nature to recoil from gossip, for which he had neither time nor patience. Finally, though, displeased that it might be said that he was concealing something, Cédric determined that he would respond to the rumours publicly. He would not deny who he was; he would lose the election, lose it by a landslide, sooner than do so.

‘Am I autistic? Perhaps I am,’ he told a journalist for Vanity Fair, and then, a few days later, an interviewer on national TV. He couldn’t say for sure because he had never been formally diagnosed.

And, anyway, he added, ‘What difference would it make?’

✲

From his earliest years, in the middle of the French countryside, his had been an insulated childhood, he recalled. The shouty red of poppies, an old bicycle rusting in the grass, busy dust motes lit by the sun and making his chest hurt: these were the delicate child’s first impressions of the world. He had had trouble breathing, whether from nerves and senses that worked overtime, or from bouts of asthma and bronchitis which laid him up for weeks on end, and his parents put an ear to his chest and gave him aspirin dissolved in a glass of fizzing water. Psssst, the glass seemed to say as he lifted it to his lips, psssst, as though it had some pressing secret to share.

He was reading on his own by the age of four, paging through books his parents had brought to his room and helped him to decipher. The paediatrician who saw him that summer was amazed. On the doctor’s desk was a newspaper and he showed its front page to the little boy. Cédric read aloud, ‘The mortal remains of Paul V I …’

‘Paul the Sixth,’ corrected the doctor.

‘… will be transferred Wednesday afternoon from C—, Cas—’

‘Castel Gandolfo.’

‘… near Rome,’ continued Cédric, ‘to St Peter’s Basilica.’

‘Bravo,’ the paediatrician said to the boy; ‘remarkable,’ he said to the parents, who were both, he learned, teachers of literature. They explained how their son spent hours every day reading and rereading his books. His favourites were long on science, books about dinosaurs and the universe. He could tell an ankylosaurus from a protoceratops, recite all the planets in the solar system, yet he did not know the word for a poodle (caniche) or the names of the seasons. (And neither of these would he learn for several more years.)

One day his father brought home from the flea market a Disney comic book, Donald in Mathmagic Land. Suddenly, little Cédric couldn’t read enough of square tree roots and imaginary triangles and birds who sang the opening digits of pi. He took a great interest in chess; it was Grandmother, he remembered, who taught him how to play. His grandmother was an elegant woman who knew her own intelligence; had she been born a man, or fifty years later, she would have become a historian. She was a direct descendant of Demetrio Stefanopoli, count of Comnène, and, through this count, of the Byzantine royal house of Komnenos.

Chess, chess and more chess. For several months this became more or less Cédric’s life, playing the royal game to the point of obsession, before his father intervened. His father confiscated his board and pieces, not wanting the six-year-old to turn into a mad prodigy. He had followed media reports of what the game had done to Bobby Fischer. He didn’t want his son to grow into a future like that. This was not long before the family moved to Toulon and Cédric began primary school.