Isaac reached awkwardly into the thin space in front of the cages and swung the great window open. It hinged horizontally, opening at the top of its five-foot height. As it opened onto the warm air, a great rush of city sounds washed in with the evening heat.

“Now,” yelled Isaac, beginning to enjoy himself. “I wash my hands of you!”

He looked around and strode back to the desk for a moment, returning with a long cane he had used many years before to point at blackboards. He poked it at the cages, knocking hooks out of eyes, fumbling till he undid latches, ripping holes in wire as thin as silk.

The fronts to the little prisons began to fall away. Isaac speeded up, opening all the doors, using his fingers where the cane was not delicate enough.

At first, the creatures within were bewildered. For many, it was weeks since they had flown. They had eaten badly. They were bored and frightened. They did not understand the sudden vista of freedom, the twilight, the smell of the air before them. But after those long moments, the first of the captives bolted for freedom.

It was an owl.

It hurled itself through the open window and sailed off towards the east, where the sky was darkest, out towards the wooded lands by Iron Bay. It glided between the Ribs on wings that hardly moved.

The escape was a signal. There was a storm of wings.

Falcons, moths, batkin, aspises, horseflies, parakeets, beetles, magpies, creatures of the upper air, little water-top skimmers, creatures of the night, the day and the gloaming burst from Isaac’s window in a shimmering explosion of camouflage and colour. The sun had sunk on the other side of the warehouse. The only light that caught the clouds of feather, fur and chitin was from streetlamps and shards of sunset reflected on the dirty river.

Isaac basked in the glory of the sight. He exhaled as if at a work of art. For a moment he looked around for a box-camera, but then he turned back and was contented just to stare.

A thousand silhouettes eddied in the air by his warehouse-home. They swirled together, aimless for a moment, then felt the currents of the air and were whisked away. Some went with the wind. Some tacked and fought the gusts and wheeled over the city. The peace of that first confused moment broke down. Aspises flew through the shoals of disoriented insects, their tiny leonine jaws closing on fat little bodies with a crunch. Hawks skewered pigeons and jackdaws and canaries. Dragonfly-snakes corkscrewed in thermals and bit at prey.