Up in the lighted room shadows of men and women crossed the blinds, and still the “Wiener Blut” went forward.

The devil was in that waltz.  He had hold of the violins and was weaving the air with scents and visions—­visions of Ascot and Henley; green lawns, gay sunshades, midsummer heat, cool rivers flowing, muslins rippled by light breezes; running horses and silken jackets; white tables heaped with roses and set with silver and crystal, jewelled fingers moving in the soft candle-light, bare necks bending, diamonds, odours, bubbles in the wine; blue water and white foam beneath the leaning shadow of sails; hot air flickering over stretches of moorland; blue again—­Mediterranean blue—­long facades, the din of bands and King Carnival parading beneath showers of blossom:—­and all this noise and warmth and scent and dazzle flung out into the frozen street for a beggar’s portion.  I had gone under.

The door of the house opposite had been free to me once—­and not six months ago; freer to me perhaps than to any other.  Did I long to pass behind it again?  I thrust both hands into my pockets for warmth, and my right hand knocked against something hard.  Yes . . . just once. . . .

Suddenly the door opened.  A man stood on the threshold for a moment while the butler behind him arranged the collar of his fur overcoat.  The high light in the portico flung the shadows of both down the crimson carpet laid on the entrance-steps.  Snow had fallen and covered the edges of the carpet, which divided it like a cascade of blood pouring from the hall into the street.  And still overhead the “Wiener Blut” went forward.

The man paused in the bright portico, his patent-leather boots twinkling under the lamp’s rays on that comfortable carpet.  I waited, expecting him to whistle for a hansom.  But he turned, gave an order to the butler, and stepping briskly down into the street, made off eastwards.  The door closed behind him.  He was the man I most hated in the world.  If I had longed to cross the threshold a while back it was to seek him, and for no other reason.

I started to follow him, my hands still in my pockets.  The snow muffled our footfalls completely, for as yet the slight north-east wind had frozen but the thinnest crust of it.  He was walking briskly, as men do in such weather, but with no appearance of hurry.  At the corner of Sloane Street he halted under a lamp, pulled out his watch, consulted it, and lit a cigarette; then set off again up the street towards Knightsbridge.

This halt of his had let me up within twenty paces of him.  He never turned his head; but went on presenting me his back, a target not to be missed.  Why not do it now?  Better now and here than in a crowded thoroughfare.  My right hand gripped the revolver more tightly.  No, there was plenty of time:  and I was curious to know what had brought Gervase out at this hour:  why he had left his guests, or his wife’s guests, to take care of themselves:  why he chose to be trudging afoot through this infernally unpleasant snow.