Three months later she became pregnant. Just as their doctor had predicted – take off the pressure and often the couple will conceive. So it had been with them. Once they had turned their attention to adopting a child, Celina had fallen pregnant. And six months later, Juan, the most recent scion of the family, had been born. Darkly handsome, an Ortega in his pram.

Hands still clasped together, Bartolomé swallowed with effort. Perhaps a reminder of his flu? Or simple rage at what he had just been told? He swallowed again, feeling the same tightening of his throat muscles as he stared at the vast expanse of floor in front of him. He liked the emptiness of his office, the cool, chilling grandeur of possessing a room so large that its brilliant architecture and size required little adornment. With the formidable Ortega collection at his disposal, Bartolomé could have covered the walls with images, but he left them blank. When he worked he liked no distractions, nothing to clutter his mind.

His mind wasn’t cluttered at that moment; it was processing the information he had received. Goya’s skull had been found. It was in the possession of Leon Golding, the one art historian Bartolomé feared. The one man he believed might solve the riddle of the Black Paintings before he could. But that wasn’t all – Bartolomé unclenched his hands, flexed his fingers, stared at the mute walls – his brother had known. The sly Gabino had known about the skull. Apparently he had even approached Golding about it, and never said a word to his brother. Never told Bartolomé the news about the greatest passion of his life. Never passed on information which would have been priceless.

Reserved and unemotional, Bartolomé struggled to maintain his calm. As a man of stunning beauty and exquisite taste, in his hands the Ortega collection had secured some magnificent works, including a Velasquez and several paintings by Guido Reni. But Bartolomé’s real passion was for Goya. The Ortegas already owned two small works, but he was always ready to acquire more. Judicious in his financial affairs and kindly in his affections, Bartolomé was, however, obsessed by the Spanish painter. In fact it was the only area of his life which had the ability to unsettle him.

Relentlessly he hunted the internet, his personal sources and auctions around the globe for more works. Over the years he had also spent prodigious amounts of money trying to solve the riddle of the Black Paintings. A queue of experts had come and gone, offering up explanations, none of which were definitive and many derivative. Bartolomé had lost count of the times he had been given Goya’s insanity, illness or fear of death as an explanation. Even hints of a sadomasochistic relationship with his mistress, Leocardia.

None of the theories rang true, and Bartolomé, with unlimited funds, became personally infatuated with the solving of the Black Paintings. At first he had been willing to hire people and ask celebrated art historians for their opinions, but as his interest festered into obsession, Bartolomé realised that he had to win. It was only right that a Spaniard should discover the truth, only correct that the wealthy and powerful Ortega family should make this cultural triumph. And, in the process, finally overshadow the thuggish reputation of their past.

So why had his brother deliberately kept the news of Goya’s skull quiet?

Because Gabino had no interest in Goya, in paintings, in heritage. His life was spent fucking and hustling, as he grubbed his way around Spanish society. As boorish and ruthless as their grandfather … Pushing back his chair, Bartolomé stood up. He moved like a dancer, light-footed, erect, a man who could feel the earth under his feet and was sure of his place on it. A man who had carried the Ortega name with pride, holding it aloft, demanding respect – not like Gabino, swaggering like a stevedore with his heritage tucked carelessly under one arm.

Surprised, Bartolomé could feel himself shaking and turned as the door opened and Celina walked in.

‘Darling,’ she said, moving over to him and kissing him lightly. She smelt of earth and Bartolomé glanced down at her hands.

‘You’ve been gardening.’

She nodded, her youthful face tipped up to look at him, her eyes green and intelligent, her hair a shade lighter from the sun.

‘You should come out – it’s cooler now. It will do you good.’ She reached up and touched his forehead. ‘Are you feeling all right?’

‘Fine.’

She wasn’t convinced. Knew him too well. ‘Bad news?’

‘No,’ he lied. ‘I’m just tired.’

The lie was difficult for him, because he trusted his wife and normally confided in her. Unlike other Ortega consorts, past and present, Celina was not excluded, partitioned off in some harem, her purpose erotic or maternal. She was her husband’s equal. Her family was French and liberal. Certainly not wealthy, but Celina had attracted Bartolomé for exactly those reasons. He wanted no organised Spanish match, no mating of business interests. He wanted love and sanctuary. In Celina he found it. And something more – a prodigious intelligence.

Their chosen exile in Switzerland suited them both, as neither was particularly social and both treasured their privacy. For all his appeal, Bartolomé was not a sensuous man and his sexual appetite was meagre. He watched his brother’s seductions with puzzlement, having never felt such lustiness himself. In truth Bartolomé had welcomed his early marriage and removal from the Spanish social scene and had been fortunate in choosing a wife whose erotic appetites were also minimal. Theirs was a marriage of understanding and mutual trust.

But despite that Bartolomé wasn’t going to tell his wife about Gabino. Too humiliated to confide, he reassured himself. At any moment his brother would tell him about the Goya skull. Gabino would phone or visit. He would.

He had to.

Le Quinta del Sordo, Madrid, Spain, 1820

Dr Arrieta was aware of flies buzzing around the bed, and flicked his hand in their direction. They scattered, settling on the nets over the window, then slowly began to creep across the ceiling, eyeing the two men below. Over the previous summer months yellow fever had crawled like a cripple over Madrid, eventually reaching the bridge over the Manzanares. But the water did not stop it. Instead the fever skimmed on the surface and hopped with the gadflies in the miasma of heat and emerald slime. Fish which had populated the river had now gone, finding the further reaches where the disease hadn’t polluted the flow. And around the Quinta del Sordo the dry earth gave up its ailing weeds to the city’s sickness.

Sweating, Dr Arrieta leaned over the bed and stared into the invalid’s waxy face. He was, he thought helplessly, already expecting to see a corpse. Surely Francisco Goya couldn’t survive another critical illness at his age? Arrieta had not been in attendance before, but had been told of his patient’s long illness in1792. Some said it had been due to a fever, but although that was a possibility, Arrieta had his doubts. He wondered instead if Goya had a serious inflammation of the brain, his blood pressure rising high enough to cause a profound stroke. A stroke which might well have resulted in deafness, depression and even hallucinations.

But even after he recovered Goya had been – and remained – profoundly deaf. And after his first illness his whole life had changed, his court existence closed off, communication hobbled, music silenced. For a man with a great libido and prodigious energy, Goya had been cruelly cowed. In silence, he had gone back to painting; had grown older, more impatient, his deafness alienating him, driving him onwards.

And inwards.

Arrieta stared at his patient. He had a queasy feeling of dread that he might be watching a great man going slowly and irrevocably mad. The steaming, red heat of the Spanish summer clotted with the guttural, unintelligible sounds the painter made in his delirium and hung, clammily, about the plastered walls. Night shadows thick with the smell of drying paint and the stagnant water outside curdled around the high altar of the restless bed. At times Goya would reach out, grasping the air. But his eyes were never open, as though what he saw was not real, not of the world, but something inescapable, inside the ruin of his teeming brain.