'He arrived just after you did and has been waiting ever since.'

I felt distinctly apprehensive. I had been hoping that the citizen in green was just an opportunist thief who had noticed something going on at the warehouse and gone in to explore as soon as he thought Frontinus and I had left.

Following me home put his presence in a different light. That degree of curiosity could not be innocent. It meant his interest in the warehouse was no coincidence. He must be some character who badly needed to know what had happened there, and to put a name to any stranger connected with the place. This spelt trouble for those of us at the Palace who were thinking we had put the conspiracy against the Emperor to bed.

While I watched, he lost his zest for spying and took himself off strolling towards the Ostia Road. I had to find out more about him. I raised an arm to Lenia, left Secunda with a smile that ought to keep her simmering, then slipped out in pursuit.

Cassius the baker, who must have been keeping an eye on the stranger, tossed me a thoughtful look and a stale bread roll as I went by.

IV

I nearly lost him on the main road. I glimpsed my mother inspecting onions by a greengrocer's stall. Judging by her grim face, the onions, like most of my lady friends, fell short of her standards. My mother had convinced herself my new job working for the Palace involved good money, simple clerical work, and keeping my tunics clean. I was reluctant to let her discover so soon that it was the same old round of trudging after villains who chose to slouch through the streets when I wanted my lunch.

It took deft footwork to avoid her without losing him. Luckily the green cloak was an unpleasant shade of viridian, easy to pick up again.

I trailed him to the river, which he crossed on the Sublician Bridge; a ten-minute hike away from civilization to the Transtiberina hovels where the street hawkers crowd when they are kicked out of the Forum after dark. The Fourteenth District had been part of Rome since my grandparents' day, but there were enough swarthy immigrants over there to make it feel alien. After my task that morning I did not care if one of them knifed me in the back.