Antonia smiled. ‘It is indeed. I shall …’ She paused. ‘I shall make my way to the Birth of Venus and absorb that. Then I shall … Oh, there is so much that I plan to do.’

The queue started to move. Under cover of the excited chatter that accompanied that, Angus was able to whisper again to Domenica. ‘She’s clearly heading for some sort of crisis. She really is. Her eyes – take a look at her eyes. Her pupils are dilated. Do you think she’s taking something?’

Domenica cast a glance at Antonia, who was standing a short distance behind them, studying a guidebook that she had extracted from the pocket of her coat.

‘She could be. It would explain this rather manic muttering about beauty. We shall just have to watch her. I propose to follow her at a discreet distance once we’re in and see what she gets up to.’

‘I’ll do the same,’ said Angus. ‘I don’t want you to follow her by yourself.’ He paused. ‘Do you think she’s dangerous?’

Domenica raised an eyebrow. ‘I’ve always taken the view that she constitutes a danger to men, but no, I don’t think that she’s likely to be violent. Still, you never know. Do you have a whistle on you?’

Angus did not.

‘A whistle can be useful in an emergency,’ said Domenica. ‘But so few people seem to carry one these days.’

They reached the admission booth and Domenica purchased tickets. Antonia stood behind Angus; he noticed that her knuckles were white from the clenching and unclenching of her fists.

They went in. ‘Now,’ said Domenica, ‘we shall all meet here in exactly three hours. Then we shall go for a late lunch over which we shall be able to discuss the treats that we’re about to see.’

‘Good,’ said Angus. ‘Quattrocento here I come!’

‘Che bellezza!’ muttered Antonia, wandering off towards the first of the galleries. ‘Oh, che bellezza!’

Domenica and Angus held back under the pretence of consulting a guidebook. Then, after a minute or two, Domenica indicated that they should discreetly make their way towards the gallery to which Antonia had been heading.

It was Angus who heard the commotion first. Grabbing Domenica by the arm, he gestured towards the source of the noise, just inside the gallery.

‘Quick,’ he said. ‘Follow me.’

The two ran in the direction of the shouting that was now plainly emanating from within. When they reached the doorway to the gallery, their worst fears were confirmed. There was Ant onia, prone on the floor, shouting and writhing, while about her stood a circle of concerned security guards. Another man in uniform was running from the opposite end of the gallery, accompanied by several young women.

Angus strode forwards, followed by Domenica.

‘Please stand back,’ said one of the security men in Italian. ‘There is nothing to see.’