Painting Mona Lisa. Jeanne Kalogridis

him, Cardinal Riario leaned forwards, looked to his left and caught sight of Giuliano. He gave Lorenzo an odd, tremulous grin, then with a snap of his head, forced his gaze back to the altar, where the priest was blessing the sacred Host.

      The lad’s movement was so peculiar, so nervous, that Lorenzo felt a faint stirring of anxiety. Florence was always full of whispers, most of which he ignored; but Nori had recently reported a rumour that Lorenzo was in danger, that an attack was being planned against him. But as usual, Nori could offer no specifics.

      Ridiculous, Lorenzo had scoffed. There will always be whispers, but we are the Medici. The Pope himself might insult us, but even he dare not lift his hand against us.

      Now, he felt a pang of doubt. Beneath the cover of his mantle, he fingered the hilt of his short sword, then gripped it tightly.

      Only seconds later, a shout came from the direction Riario had glanced – a man’s voice, the words unintelligible, impassioned. Immediately after, the bells of Giotto’s campanile began to toll.

      At that moment Lorenzo knew that Nori’s so-called rumours were fact.

      The front two rows of men broke rank and the scene became a clumsy dance of moving bodies. In the near distance, a woman screamed. Salviati disappeared; the young Cardinal flung himself at the altar and knelt, sobbing uncontrollably. Guglielmo de’ Pazzi, clearly terrified, began wringing his hands and wailing: ‘I am no traitor! I knew nothing of this! Nothing! Before God, Lorenzo, I am completely innocent!’

      Lorenzo did not see the hand that reached from behind him to settle lightly on his left shoulder – but he felt it as though it were a lightning bolt. With a grace and strength that came from years of swordsmanship, he pushed forwards out of the unseen enemy’s grasp, drew his sword, and whirled about.

      During the sudden movement, a keen blade grazed him just below the right ear; involuntarily, he gasped at the sensation of his tender skin parting, of warm liquid flowing down his neck onto his shoulder. But he stayed on his feet and held up his sword, ready to block further attacks.

      Lorenzo faced two priests: one trembling behind a small shield, half-heartedly clutching a sword as he glanced at the crowd scrambling for the cathedral doors. But he was obliged to turn his attention to Lorenzo’s personal attendant, Marco, a muscular man who, though no expert with a sword, made up for it with brute strength and enthusiasm.

      The second priest – wild-eyed and intent on Lorenzo – raised his weapon for a second attempt.

      Lorenzo parried once, twice. Haggard, pale-skinned, unshaven, this priest had the fiery eyes, the open, contorted mouth of a madman. He also had the strength of one, and Lorenzo came close to buckling beneath his blows. Steel clashed against steel, ringing off the high ceilings of the now mostly-deserted cathedral.

      The two fighters locked blades, pressing hilt against hilt with a ferocity that caused Lorenzo’s hand to tremble. He stared into the eyes of his determined enemy, and drew in a breath at the emotion he saw there.

      As the two stood with blades crossed, neither willing to give way, Lorenzo half shouted: ‘Why should you hate me so?’

      He meant the question sincerely. He had always wished the best for Florence and her citizens. He did not understand the resentment others felt at the utterance of the name Medici.

      ‘For God,’ the priest said. His face was a mere hand’s breadth from his intended victim’s. Sweat ran down his pale forehead; his breath was hot upon Lorenzo’s cheek. His nose was long, narrow, aristocratic; he probably came from an old, respected family. ‘For the love of God!’ And he drew back his weapon so forcefully that Lorenzo staggered forwards, perilously close to the blade.

      Before the opponent could shed more blood, Francesco Nori stepped in front of Lorenzo with his sword drawn. Other friends and supporters began to close in around the would-be assassins. Lorenzo became vaguely aware of the presence of Poliziano, of the aged and portly architect Michelozzo, of the family sculptor Verrochio, of his business associate Antonio Ridolfo, of the socialite Sigismondo della Stuffa. This crowd sealed him off from his attacker and began to press him towards the altar.

      Lorenzo resisted. ‘Giuliano!’ he cried. ‘Brother, where are you?’

      ‘We will find and protect him. Now, go!’ Nori ordered, gesturing with his chin towards the altar, where the priests, in their alarm, had dropped the full chalice, staining the altar-cloth with wine.

      Lorenzo hesitated.

      ‘Go!’ Nori shouted again. ‘They are headed here! Go past them, to the north sacristy!’

      Lorenzo had no idea who they were, but he acted. Still clutching his sword, he hurdled over the low railing and leapt into the octagonal carved wooden structure that housed the choir. Cherubic boys shrieked as they scattered, their white robes flapping like the wings of startled birds.

      Followed by his protectors, Lorenzo pushed his way through the flailing choir and staggered towards the great altar. The astringent smoke of frankincense mixed with the fragrance of spilt wine; two tall, heavy candelabra were ablaze. The priest and his two deacons now encircled the blubbering Riario protectively. Lorenzo blinked at them. The afterimage from the lit tapers left him near blinded, and in an instant of dizziness, he put his free hand to his neck; it came away bloodied.

      Yet he willed himself, for Giuliano’s sake, not to faint. He could not permit himself a moment’s weakness – not until his brother was safe.

      At the moment that Lorenzo ran north across the altar, Francesco de’ Pazzi and Bernardo Baroncelli were down in the sanctuary, pushing their way south, clearly unaware that they were missing their intended target.

      Lorenzo stopped mid-stride to gape at them, causing collisions within his trailing entourage.

      Baroncelli led the way, brandishing a long knife and shouting unintelligibly. Francesco was limping badly; his thigh was bloodied, his tunic spattered with crimson.

      Lorenzo strained to see past those surrounding him, to look beyond the moving bodies below to the place where his brother had been standing, but his view was obstructed.

      ‘Giuliano!’ he screamed, with all the strength he possessed, praying he would be heard above the pandemonium. ‘Giuliano …! Where are you? Brother, speak to me!’

      The crowd closed around him. ‘It’s all right,’ someone said, in a tone so dubious it failed to provoke the comfort it intended.

      It was not all right that Giuliano should be missing. From the day of his father’s death, Lorenzo had cared for his brother with a love both fraternal and paternal.

      ‘Giuliano!’ Lorenzo screamed again. ‘Giuliano …!’

      ‘He is not there,’ a muffled voice replied. Thinking this meant that his brother had moved south to find him, Lorenzo turned back in that direction, where his friends still fought the assassins. The smaller priest with the shield had fled altogether, but the madman remained, though he was losing the battle with Marco. Giuliano was nowhere to be seen.

      Discouraged, Lorenzo began to turn away, but the glint of swift-moving steel caught his eye and compelled him to look back.

      The blade belonged to Bernardo Baroncelli. With a viciousness Lorenzo would never have dreamt him capable of, Baroncelli ran his long knife deep into the pit of Francesco Nori’s stomach. Nori’s eyes bulged as he stared down at the intrusion, and his lips formed a small, perfect o as he fell backwards, sliding off Baroncelli’s sword.

      Lorenzo let go a sob. Poliziano and della Stuffa took his shoulders and pushed him away, across the altar and towards the infinitely tall doors of the sacristy. ‘Get Francesco!’ he begged them. ‘Someone bring Francesco. He is still alive, I know it!’

      He tried again to turn, to call out for his brother, but this time his people would not let him slow their relentless march to the sacristy. Lorenzo felt a physical pain in his chest, a pressure so brutal he thought his heart