It banked towards the huge gas cylinders in Echomire, spiralled back easily, slipped under a layer of disturbed air and flew steeply down towards Mog Station, passing under the skyrails too fast to be seen, disappearing into the Pincod roofscape.

Isaac was not lost in his numbers.

He looked up every few minutes at Lin, who slept and moved her arms and wriggled like a helpless grub. His eyes looked as if they had never been lit up.

In the early afternoon, when he had worked for an hour, an hour and a half, he heard something clatter in the yard below. Half a minute later there were footsteps on the stairs.

Isaac froze and waited for them to stop, to disappear into one of the junkies’ rooms. They did not. They moved with a deliberate tread up the final two flights, making their careful way up the noisome steps and halting outside his door.

Isaac was still. His heart beat quickly in alarm. He looked around wildly for his gun.

There was a knock at the door. Isaac said nothing.

After a moment, whoever was outside knocked again: not hard, but rhythmically and insistently, repeatedly. Isaac stalked closer, trying to be quiet. He saw Lin twisting uncomfortably at the sound.

There was a voice outside the door, a weird, harsh, familiar voice. It was all grating treble, and Isaac could not understand it, but he reached out for the door suddenly, unsettled and aggressive and ready for trouble. Rudgutter would send a whole damn squadron, he thought as his hand closed on the handle, it’s bound to be some junkie begging. And although he did not believe that, he was reassured that it was not the militia, or Motley’s men.

He pulled the door open.

Standing before him on the unlit stairs, leaning slightly forward, sleek feathered head mottled like dry leaves, beak curved and glinting like an exotic weapon, was a garuda.

He saw instantly that it was not Yagharek.

Its wings rose up and swelled around it like a corona, vast and magnificent, feathered in ochre and smooth red-stained brown.

Isaac had forgotten what an uncrippled garuda looked like. He had forgotten the extraordinary scale and grandeur of those wings.

He understood what was happening almost immediately, in some inchoate and unstructured way. A wordless intimation hit him.

Following it by a fraction of a second came a massive gust of doubt and alarm and curiosity and a slew of questions.

“Who the fuck are you?” he breathed, and: “What are you fucking doing here? How did you find me . . . What . . .” Half-answers came unbidden to him. He stepped back from the threshold quickly, trying to banish them.

“Grim . . . neb . . . lin . . .” The garuda struggled with his name. It sounded as if he was a dæmon being invoked. Isaac jerked his arm quickly for the garuda to follow him into the little room. He closed the door and pushed the chair back up against it.