‘Well, Libertus, it’s not like you to fail. But you brought it on yourself. No one asked you to go rushing off, asking questions in Corinium like that. I’m not surprised that Publius was quibbling at the bill. You’re lucky that he paid it.’

I muttered something to the effect that I was glad he had.

‘He’s fallen out severely with Lavinius, of course – says that the fellow struck a deal with him and has failed to deliver what he promised. He’s threatening to sue. I think he finally agreed to meet your costs mostly because Lavinius did not approve of you.’

It was after dinner in his villa, and Marcus was drinking wine, reclining on his dining couch and eating little pastry-cakes left over from the meal. He had dismissed the other diners and the slaves, so we were all alone, but he hadn’t asked me to partake of anything. It was part of my penance. He had sent for me as soon as he knew that I was home, and I had not had time to eat, but he hadn’t finished with his diatribe.

‘Once it was obvious that Audelia was dead, I don’t know why you didn’t let the matter rest. Even you can hardly expect to solve a case of Druid sorcery – I suppose I should be glad that you escaped unscathed. So I forgive you. I can’t answer for your wife.’

It was true that she was angry, but I knew she would relent. It was mostly worry because I’d not been home for days. And she sensed that I was hiding something that I wouldn’t share. Not yet. I would confide in Gwellia as I always did, and tell her everything – even show her the poison-phial which had duly turned up in Priscilla’s midden-pile – but not until that little family were far away in Gaul.

In the meantime, I would have to live with her rebukes. I had not even earned a quadrans for my time. My toga was crumpled and in need of laundering and couldn’t I have let her know a little sooner where I was?

But I knew for certain that when I got home again there would be my favourite hot stew awaiting me, and that oatcakes for my breakfast were standing by to bake. Like Paulinus, I was a lucky man.

Marcus scooped up the remaining pastry-cakes, put them on a serving plate and handed them to me. ‘Take these home to her. It might win you a smile.’ He gave his languid grin. ‘In the meantime, I’ve had enough tonight. I’ll see you in the morning. I’ve got a job for you. A little mystery I’d like you to sort out. If you haven’t entirely lost the gift, that is.’ He chuckled and waved me out of the triclinium.

I walked home in the darkness, clutching the plate of cakes and trying not to spill them on the uneven lane. It was cold and drizzling and the wind was getting up, but I was thankful for my lot. I had a cheerful home and a wife who cared for me, a healthy grandson by my adopted son, good slaves to serve me and enough to eat. Who could ask for more? I thought of a gentle couple who had been forced to dreadful lengths by family treachery, of terrible diseases that carried off male heirs, and of a child, not many miles away, whose whole world was silence.

I fingered the piece of slate that I carried in my pouch and went in to see my wife. She was no ethereal goddess, she was short and stoutish and her face was lined, but I loved her dearly and I always had.

When she had finished chiding me and I’d enjoyed the stew, I would show her the chalk portrait and tell her it was me – not a tree with fingers. I knew that she would laugh.