Momus, I was certain, never had a slave grandmama who was cosy with the old Empress. He must have crawled out of an egg in a streak of hot slime somewhere. Any horrible siblings were basking in rich men’s zoos or their heads were on walls as hunters’ trophies.

Momus reacted eagerly to news of the spy’s implication in sordid crimes, until I hankered for Laeta’s measured thoughtfulness instead. Momus even promised to help—though he freely agreed it was hard to see what he could do.

‘Momus, I still don’t think the Claudii showed up and got jobs with the spy by accident. Are you ever going to tell me what you know about them?’

‘Falco, if I knew how they control him, I’d be controlling him myself.’

‘Do you admit you’ve put in people to watch him?’

‘Of course I haven’t,’ he lied.

I left, reflecting ruefully that Momus had always been useless.

There was one more possibility.

Anacrites sometimes used a freelance on very special assignments, a woman. Helena and I had run into her a few times, and although I had a professional respect for her, we viewed her warily. She killed for Anacrites, killed to order. She took a pride in a beautiful performance, whether it was death or dancing. Dance was her cover. Just like her assassinations, it was clean, prepared in every detail, immaculate and took your breath away. Her talent gave her access to people Anacrites wished to remove; distracted by her brilliance, they were at her mercy. As often as not, no connection was made between her dancing and the discovery of a shocking corpse. Her name was Perella. She used a thin-bladed knife to slit her victims’ throats. Knowing her method, I never let her stand behind me.

The first time I met Perella, before I knew her significance, it was at her home. Though a few years had passed, I managed to find the place again: a small apartment near the Esquiline, inexpensive but endurable. She let me in, barely surprised to see me. I was given a bowl of nuts and a beaker of barley water, urged to take the good chair and the footstool. It was like visiting a great-aunt, one who looked demure but who would reminisce about times when she juggled three lovers all at once—and who was rumoured to still do it, passing them on to the baker’s wife, when she felt tired.

What made me remember Perella was my encounter with the mystic Alis. Perella, too, was of mature age and build; in fact more years of age than it was kind to mention. The skilled diva remained supple. She had power too; not so long before, I saw her kick a man in the privates so hard she wrote off all chance of him producing children.

‘Didius Falco! Whenever I see you, I feel apprehensive.’