Making their way outside, they blinked as their eyes adjusted to the bright sunlight. At once the cella's calm was replaced by the noise of the crowds filling the open area between the temple and the statue of Jupiter. The cries of food vendors competed with acrobats, street performers and peddlers of tat. Here a mother scolded her wayward children, and there a bevy of painted whores stood, doing their best to encourage men down the nearest alley. Cripples, lepers and the diseased filled every available space, presenting a forest of outstretched palms for those kind enough to open their purses.

'What did you ask for?' Romulus asked Mattius.

'Nothing,' answered the urchin.

'Yet you wanted to come in with us.'

'To give thanks,' came the reply. 'And to fulfil my vow.'

Romulus gave him a quizzical look.

'You took me away from my stepfather. Jupiter must be responsible for that,' said Mattius seriously. 'I had been praying to him every night, asking for his help. Then you came along.'

'I see.' Romulus smiled indulgently, before realising that the boy's belief was no different to his. How else could one explain the removal of a huge obstacle from one's life? In his case, it had been the impossibilities of surviving Carrhae and returning to Rome, while in Mattius' it was escaping from the cruelty he suffered daily at home.

When he looked up, Tarquinius was already heading for the men who sold animals for sacrifice. Romulus hurried after him, buying a healthy-looking fawn-coloured kid that caught his eye. The haruspex settled for a plump black hen with bright eyes and clean plumage, and together they shouldered past the soothsayers who instantly converged, offering to reveal their wondrous futures. Mattius bobbed in their wake, amazed at the contempt his friends showed towards the robed augurs. He was even more flabbergasted a few moments later when Tarquinius found a spot right between Jupiter's feet.

'He's a soothsayer?' Mattius whispered.

Romulus nodded.

'Hold this.' Tarquinius handed the hen to Mattius, who accepted it with a nervous smile.

Clearing away the trinkets and small offerings left there by hopeful citizens, the haruspex eyed the paving slabs, which were covered in dark red smears. Romulus saw them too, and understood Tarquinius' purpose. The bloodstains told their own story.

Although he had never seen it done, other people had sacrificed here before.

Taking a deep breath, Tarquinius drew his dagger. 'Give me the bird,' he said in a deep voice. 'It is time.'

As Mattius obeyed, beads of nervous sweat broke out on Romulus' forehead.

Jupiter, Optimus Maximus, tell me what to do, he prayed. 'Welcome,' said Fabiola, inclining her head graciously at Caius Trebonius. 'All the others are here.'

'Good.' Trebonius smiled. A short, balding man in middle age, he still had the muscular physique of someone much younger. With shrewd brown eyes and high cheekbones, he was not dissimilar in appearance to Caesar. His height was the most noticeable difference, yet it did not detract from his presence. Like most of the Roman nobility, he carried himself with the utmost confidence. 'What of Brutus?'

Fabiola shook her head. 'He can't bring himself to join us yet.'

'A shame.' Trebonius sighed. 'Such a son of Rome would be a great addition to our number.' With a courteous bow, he headed to the largest of the bedchambers, which had been converted to a meeting room.

Fabiola followed, still not quite believing that someone else who had served the dictator so faithfully – Trebonius had been a suffect consul the year before – now wanted to kill him. Yet he had been one of the first to join her conspiracy. Responding promptly to her invitation, Trebonius had arrived at the brothel to be treated to a lingering massage by Fabiola herself. This was before three of her best-looking prostitutes had led him, unprotesting, away. 'Do anything he requests,' Fabiola had ordered the trio earlier. 'Absolutely anything.' They all nodded, eagerly eyeing the weighty purses she'd promised them afterwards.

A couple of hours later, Trebonius had been in the most affable of moods. Enjoying a cup of fine wine with Fabiola in the brothel's newly refurbished courtyard, he had been quick to offer his condemnation of Caesar. 'The man's lost the plot. Wearing those red calf-length boots like he's a king of Alba Longa. As for topping his costume off with a gilded laurel wreath, well…' He patted his thinning hair and smiled. 'What the gods give, the gods take away. It isn't for us to hide it under fancy headgear.'

Laughing at his joke, Fabiola had leaned over to refill his cup, making sure that her cleavage was on full display. 'Some of the people think he's a sovereign already,' she said, deliberately alluding to the recent episode when Caesar had been hailed with shouts of 'king' during a procession into the city. Reports of the incident had swept through Rome like wildfire.

Trebonius had scowled. 'So we're supposed to swallow the lie that he's not king, but Caesar. Pah! It's laughable.'

He had gone on to describe why Caesar had to be stopped. It wasn't the dictator's manner or treatment of those who voiced their opposition to him, for in these cases Caesar continued to be mild-mannered and forgiving. Even the tribunes who had ordered the arrest of the man who'd first shouted 'king' had escaped with light punishments. Sulla would not have been so lenient, Trebonius admitted. Nor would other previous dictators. It was the absolute power that Caesar had gathered unto himself, eliminating virtually all the power of the Senate and elected magistrates. Half a millennium of democracy had been swept away in less than two years.

Fabiola had deployed the same tactic with the other prominent nobles whom Brutus had mentioned. Although she'd been prepared to sleep with all the men if she had to, that had not proved necessary, which helped her feel better about herself and her promise to Brutus. Thankfully, the tide of ill feeling against Caesar was running high, and all the disgruntled needed was the catalyst to bring them together. Fabiola had proved to be this medium, and in less than a week she had enlisted the help of Marcus Brutus, Cassius Longinus, Servius Galba and Lucius Basilus. Marcus Brutus was her lover's cousin, and the son of Servilia, Caesar's long-term lover. Despite this, he had taken the part of the Republicans and had fought with them at Pharsalus. Welcomed back into the fold afterwards thanks to Caesar's magnanimity, he had secured the same pardon for Cassius Longinus, who had served Crassus in Parthia. It was no surprise, therefore, that both men joined the conspiracy together. Marcus Brutus' reasons for taking part were simple. Like Trebonius, he felt aggrieved at the manner in which Caesar had assumed total power, reducing able men like himself to impotent bystanders. However, like Decimus Brutus, Fabiola's lover, he was also a member of the family who had reputedly deposed the last king of Rome five centuries before. In addition, he was the nephew of Cato, the Republican orator who, rather than live under Caesar's rule, had committed suicide after Thapsus. This act had turned Cato into the epitome of Roman aristocratic virtue, and driven Marcus Brutus to write a pamphlet in his praise. Now he was showing his true colours and, in his eyes, his Roman honour, by taking part in the conspiracy.

Fabiola wanted more than five eminent men, however. Fame and public recognition did not guarantee success. Moreover, any attempt on the dictator's life risked onlookers coming to his aid. Despite Caesar's disbanding of his loyal Spanish bodyguards at the beginning of the year, the public and most senators still loved him dearly, and might intervene on his behalf. She could see it happening. More recruits were needed.

Fabiola's prayers had been answered nearly four weeks before, during the Lupercalia, the ancient fertility festival. Watched by huge crowds, Antonius had publicly offered Caesar a royal diadem and asked him to become king. Caesar had demurred twice, ordering the crown to be taken instead to the temple of Jupiter. This clumsy attempt by the dictator to allay suspicions about his aspirations to the monarchy, had immediately been negated by a soothsayer's prediction that Parthia could only be conquered by a king. Another soon followed it, alleging that the Senate would vote Caesar the kingship of everywhere except Italy.