Gregor is feeding pigeons down in the park when the sirens go off.

A stoop-shouldered forty-something male in a dark suit, pale-skinned and thin, he pays no attention at first: the birds hold his attention. He stands at the side of a tarmac path, surrounded by damp grass that appears to have been sprayed with concrete dust, and digs into the outer pocket of his raincoat for a final handful of stale bread-crumbs. Filthy, soot-blackened city pigeons with malformed feet jostle with plump white-collared wood pigeons, pecking and lunging for morsels. Gregor doesn't smile. What to him is a handful of stale bread, is a deadly business for the birds: a matter of survival. The avian struggle for survival runs parallel to the human condition, he ponders. It's all a matter of limited resources and critical positioning. Of intervention by agencies beyond their bird-brained understanding, dropping treats for them to fight over. Then the air raid sirens start up.

The pigeons scatter for the treetops with a clatter of wings. Gregor straightens and looks round. It's not just one siren, and not just a test: a policeman is pedaling his bicycle along the path towards him, waving one-handed. "You there! Take cover!"

Gregor turns and presents his identity card. "Where is the nearest shelter?"

The constable points towards a public convenience thirty yards away. "The basement there. If you can't make it inside, you'll have to take cover behind the east wall — if you're caught in the open, just duck and cover in the nearest low spot. Now go!" The cop hops back on his black boneshaker and is off down the footpath before Gregor can frame a reply. Shaking his head, he walks towards the public toilet and goes inside.

It's early spring, a weekday morning, and the toilet attendant seems to be taking the emergency as a personal comment on the cleanliness of his porcelain.