The list of possible crises sounded like an excuse in retrospect. Then the subtle way Laeta failed to meet my eye alerted me. Dear gods. I could hardly believe what must have happened: 'So, Claudius Laeta, let me be quite clear: Rutilius Gallicus brought the priestess back to Rome with him – for "safety" – then he let her escape here?'

Veleda was a stupendously influential barbarian, a famous enemy who once rabble-roused a whole continent into revolt against Rome. She hated us. She hated everything we represented. She had united northern Europe while we were preoccupied with our leadership tussles, and at the height of her activity she nearly lost us Batavia, Gaul and Germany. And now, Laeta was telling me, she was on the loose, right inside our city.

Claudius Laeta pursed his lips. He had the sorrowful expression of a top official who is absolutely determined his department will not be blamed for this. 'Is it your problem?' I murmured mischievously. 'Chief Spy's remit,' he announced firmly. 'Then it's everybody's problem!' 'You are very frank about your differences with Anacrites, Falco.' 'Someone has to be open. That fool will do a lot of damage if he isn't stopped.' 'We believe him to be competent.' 'Then you're nuts.' We were both silent. I was thinking about the implications of Veleda's escape. It was not that she could launch a military attack here. But her presence right in Rome was a disaster. That she had been imported by an ex-consul, a high-ranking provincial administrator, one of the Emperor's favourites, would damage public confidence. Rutilius Gallicus had been stupid. There would be outrage and dismay. Belief in the Emperor would shrink. The army would look pitiful. Rutilius – well, few people had heard much of Rutilius, except in Germany. But if word got back there, the effect on the province of Germany could be dangerous. Veleda was still a big name on both sides of the River Rhenus. As a so-called prophetess, the woman had always caused a frisson of terror that was out of proportion to her real influence; still, she had summoned up armies of rebels, and those rebels had wreaked havoc. 'Now she's free in Rome – and you've sent for me.' 'You have met her, Falco. You will recognise her.' 'As simple as that?' He knew nothing. Veleda was of striking appearance: the first thing she would do was dye her hair. Most Roman women wanted to go blonde, but one visit to a cosmetic pharmacy would have Veleda well disguised.

'You may charge a premium.' Laeta made me sound mercenary. He ignored the fact that he himself received a big annual salary – plus bribes – plus pension – plus legacy, if the Emperor died – whereas I was stuck with whatever I could claw together on a freelance basis. 'This is a national emergency. Titus reckons you have the skills, Falco.'

He mentioned the fee, and I managed not to whistle. The Palace saw this as an emergency all right.

I took the job. Laeta then told me the background. It was worse than I thought. Missions from the Palace always were. Not many were as bad as this, but as soon as I had heard Veleda's name I had known this particular fiasco would be special. Rutilius Gallicus had arrived back in Italy several weeks ago, was debriefed at the Palace, caught up with the news in the Forum and from his noble acquaintances, then swanned off north to Augusta Taurinorum, where his family lived. That's right up close to the Alps. I mused that his background should have given him sympathies with the barbarians in Germany; he had been born and bred right next door to them. He was practically German himself

I had met his rather provincial wife, Minicia Paetina. She did not take to me. It was mutual. She had attended the poetry recital Rutilius and I once gave together, where she made it clear she thought me a plebeian upstart, unfit to wipe her fellow's nose. The fact that our audience openly preferred my snappy satires to his endless extracts from a second-rate epic did not improve Minicia's attitude.

The audience were no help, in fact. Rutilius Gallicus had invited Domitian Caesar as his guest of honour, whereas I was supported by cat-calling members of my Aventine family. From memory, Anacrites had been there, too. I could not remember whether this was in the ghasdy period when he tried moving in on my sister Maia or the even worse episode when everyone thought the Spy had made himself my mother's gigolo.

Helena Justina had been polite to Minicia Paetina, and vice versa, but we were generally glad when the Rutilii went home. I could imagine the kind of stiff Saturnalia they were now about to enjoy at Augusta Taurinorum. 'As a special treat, we can all wear informal tunics at dinner, instead of togas…' 'There's no chance Rutilius will cut short his leave and pop back here to sort out his mess?' 'No chance at all, Falco.'

As for Veleda, Laeta said Rutilius had brought her to Rome, where she was ensconced in a safe house. She had to be put somewhere. Burying her in a prison cell for the next couple of years, until Rutilius reached the end of his tour as governor, was not an option. Veleda would never have survived the dirt and disease. No point having a famous rebel die of jail fever. She must be kept fit and looking ferocious for the triumphal procession. A bonus would be to claim she was a virgin; by tradition she would be formally raped by her jailer just before her execution. Rome loves that kind of smut. So no one would want any dewy-eyed junior jailers falling in love with her and comforting her in the cell, let alone prankster sons of consuls bribing their way in for a quick thrill on the straw.

Priestesses always call themselves virgins. They have to clothe themselves in mystery. But Veleda had had at least one fling in the past. I knew who she had had it with too. Why do you think she gave us the boat? 'Tell me about your so-called safe house, Laeta.'

'Not mine!' I wondered whose. Would Anacrites have fixed it up? 'All necessary checks were carried out, Falco. There were rigorous measures in place. Her host is absolutely reliable. She gave us her parole as well. It was perfectly secure.' Officialdom's usual excuses. I knew how much they meant. 'So it's incredible, is it, that she somehow got out? Who was the lucky host?' 'Quadrumatus Labeo.' Never heard of him. 'Who was in charge of security?' 'Ab!' Laeta's immediate enthusiasm for the subject told me he was in the clear. 'That's an interesting point, Falco.'

'In Palatine argot, an "interesting point" is generally a complete rat's arse…' I squeezed Laeta until he admitted the mess: Rutilius Gallicus had brought Veleda home with an escort of troops from Germany. Then confusion set in. The legionaries assumed that they had handed over responsibility to the Praetorian Guard; the soldiers all expected to bugger off to brothels and winebars for three months until they had to take Rutilius back to Germany. Nobody told the Praetorians they had acquired the magic maiden. 'So, Laeta. Who should have told the Praetorians? Rutilius himself?' 'Oh he has no remit in Rome. And he is a stickler for propriety.' 'Of course he is! So the stickler jumped into a carriage and rushed north, with his Saturnalia presents stuffed in the luggage box… Did Titus Caesar know Veleda was here?'

'Don't blame him. Titus may be nominally commander of the Praetorians, yet he does not issue orders of the day. His role is ceremonial -' 'He'll certainly give a ceremonial bollocking to the Guards who watched her flit!' 'Don't forget, Falco, it is supposed to be a secret that she ever arrived. ' 'So if it's a secret, did anyone notify Anacrites?' 'Anacrites bloody well knows now!' muttered Laeta tetchily. 'He has been assigned responsibility for finding her.' This was worse than I had thought. 'Then I repeat: did he know before?' 'I have no idea.' 'Get away!' 'I am not privy to security policy.' 'But you're privy to the balls-up! Next awkward question then: if Anacrites has oversight of the recovery operation, why are you commissioning me? Does he know I'm to be involved?'