It was the date which caught his notice. Ten years previous, almost to the day, and within less than a month of Justinian’s restoration to the throne after he had been deposed and his nose had been slit. The mutilation was intended to disqualify him from the purple for ever. Justinian had refused to accept this limitation.

His return involved a rather obscure episode which Katāros happened to know. When Justinian had escaped his exile in Krim, he sailed in secret to the shores of Thrace, whence he travelled overland to the outer wall of the city and was then, somehow, smuggled inside, in time to lead the coup that put him back on the throne. The tale didn’t relate how he had entered the city. There were rumours – probably originating with Justinian himself – that it had been the Holy Virgin herself who had intervened, miraculously spiriting him through the walls. Manifest nonsense, Katāros was certain. Nevertheless, Justinian had got inside.

The cogs of logic began to turn in Katāros’s mind. A wildly inflated gift from a man hardly known for his piety. A pay-off, perhaps – but for what? ‘To the Holy Virgin, who opened the gates of blessing and glory when all were sealed.’ Given the timings, the timings—

The more Katāros thought about it, the more certain he became.

It was well before the first hour when he jumped down from the wagon and paid the driver. At the open cistern of Aetius, the great thoroughfare of the Mese forked. He had already resolved to cover the rest of the distance to Blachernae on foot, picking his way along the pathways that bounded the meadows and orchards carpeting the Sixth Hill.

He was dressed in a long drab tunic under a cloak of darker wool with the hood pulled well forward. Before he had left the palace his unpainted face had looked perfectly ordinary in the mirror, and with his hood up at this hour no one would pay him any heed.

The basilica of St Mary stood a little below the Palace of Blachernae, which sat perched on its rock in splendid solitude at the northernmost point of the city overlooking the headwaters of the Horn. The land walls ran down the ridgeline, blistering outwards like a carbuncle to enclose the palace within their protection, and rising not half an arrow’s flight away.

He went inside. The church was quite deserted. It was an hour at least before even the most devout would be on their knees. The still air felt cool but his mind was burning with uncertainty and impatience.