But there was more to it than that. With the evening came a more definite sense of suspicion within the crowded squares. Perhaps she’d been blind to it earlier, in the brilliant sunlight, surrounded by the daytime sounds of work and enthusiasm. But now in the twilight, with the bells echoing in a constant susurrus of minor tones, she felt … watched. Observed. Spied upon.

Eyes glinted behind masks, and people murmured to each other in corners. And every time she passed someone, she had an urge to look back and see if they were watching her.

Irene paused to buy a penny’s worth of sugared nuts from a street vendor and asked casually, ‘Which way is the opera house from here?’

‘Which one?’ the street vendor asked, tugging his apron straight with a weary sigh. ‘La Fenice?’

Yes, that was what Aunt Isra had said. And it was one of the biggest and most spectacular opera houses in Europe, in a large number of alternates. Where else would one auction off a dragon at midnight? ‘Yes, if you please,’ she said eagerly.

‘Ah, now that isn’t far,’ the vendor said, and rattled off a string of directions. ‘Say a prayer to the Virgin for me as you pass her church, young lady, and I hope that you have a good evening.’

Irene hoped so too, as she smiled behind the mask and continued on, tucking the packet of nuts into an inner pocket. She would gladly have eaten them, as she was feeling famished. But she couldn’t eat anything without removing her mask, and she didn’t feel like tempting fate that much.

As she came closer, she realized there was no chance of getting lost. She only had to follow the noise.

She heard the roaring crowd outside La Fenice well before she saw it. This was not one of those cities - such as the many versions of London - where people queued up politely before major cultural events. The mob was a heaving, swirling mass of people. Good. All the more cover for me. Soon she was lost in its wild enthusiasm, enthusiastic anticipation and anticipatory friendliness - all of it containing just a hint that things might go over the edge, if the crowd became too excited. Men in uniform surrounded the opera house and stood along the bank of the canal, and several nicer-than-usual gondolas displaying coloured pennants were moored alongside.

Irene was again grateful for her mask, and she was far from being the only masked person in the crowd. Both men and women, well dressed or more poorly clad, had covered their faces, and the last of the sunlight turned eye slits into dark, suspicious hollows.

She drifted inconspicuously into the rear of a medium-sized group of unmasked men and women who were sharing bottles of wine and loudly discussing the main singers in the night’s performance. ‘How long till it starts?’ she asked one of the men.

He squinted at her a little blurrily, passing his bottle to the woman next to him. ‘In five minutes, darling. They’re already tuning up for the overture. We won’t have a chance to get in until the interval. Were you waiting for someone?’

No chance of getting in round the front, then. She’d have to try the stage door around the back, or wait for the interval. And this must mean an actual opera was about to be performed - it was an opera house, after all. Maybe it was a warm-up for the auction to come? A bit of casual eavesdropping made it clear that the group was expecting Tosca, and gave her some additional information on the performers, their voices and their personal habits. ‘I think I see him over there,’ she murmured as she sidled away from them.

It took fifteen minutes to circle round to the back of the opera house and find the stage door. It then took several coins from the money that Silver had given her to bribe her way inside.

The backstage corridors were functional rather than beautiful, and full of people - the chorus, stagehands, guards, runners, and two men carrying a stage dummy on a stretcher with a dramatic bloodstain over the chest. It was no place for a bystander, and Irene made her way to the front of the house as quickly as she could. It was all marble and expensive wood here, a far cry from the more pragmatic backstage. She could see a wide staircase and a brightly lit foyer with paintings and frescos, but she stayed in the shadows.

She’d been able to hear the music quite well backstage, well enough to recognize that they were into the first act, but not that far in. She needed to get a sense of the place’s layout. And if she happened to overhear guards talking about incoming deliveries of dragons for an auction at midnight, so much the better.

The back of her neck prickled: someone was watching her. She turned slightly to glance unobtrusively over her shoulder, and saw that a man was indeed coming down the corridor towards her. Wait, not just any man. He’d been one of the people at the stage door when she came in, loitering there along with half a dozen others.

Over twenty years’ experience kicked in as she began to stroll casually down the corridor away from him. This was not a coincidence. She’d been spotted, which suggested that he’d been at the door to watch for her in particular. This was very definitely not good. She needed to get rid of him - either lose him or get him alone in a dark corner, knock him out and slip away - then change her appearance as much as possible and stay out of view.

The corridor ahead branched to right and left. Irene chose left at random, turned and nearly bumped into another man. ‘Excuse me,’ she murmured in Italian, ducking in a quick curtsey.

‘Grab her,’ the man from behind said, his voice pitched just loud enough to reach them, but not the boxes or the auditorium. He had an unpleasantly professional tone.

Damn. Irene converted her curtsey into a straight punch into the closer man’s stomach, stepped past him, kicked the back of his knee as he bent over off-balance and ran for it as he went down. This was too public a place to stand and fight.