'Ah, Chelius! Yes, I see. We must get the whole business complete before we strike. Has old Blenkiron had any luck?'

'Your guess about the "Deep-breathing" advertis.e.m.e.nt was very clever, d.i.c.k. It was true, and it may give us Chelius. I must leave Mr Blenkiron to tell you how. But the trouble is this. We know something of the doings of someone who may be Chelius, but we can't link them with Ivery. We know that Ivery is Bommaerts, and our hope is to link Bommaerts with Chelius. That's why I came here. I was trying to burgle this escritoire in an amateur way. It's a bad piece of fake Empire and deserves smashing.'

I could see that Mary was eager to get my mind back to business, and with some difficulty I clambered down from the exultant heights. The intoxication of the thing was on me-the winter night, the circle of light in that dreary room, the sudden coming together of two souls from the ends of the earth, the realization of my wildest hopes, the gilding and glorifying of all the future. But she had always twice as much wisdom as me, and we were in the midst of a campaign which had no use for day-dreaming. I turned my attention to the desk.

It was a flat table with drawers, and at the back a half-circle of more drawers with a central cupboard. I tilted it up and most of the drawers slid out, empty of anything but dust. I forced two open with my knife and they held empty cigar boxes. Only the cupboard remained, and that appeared to be locked. I wedged a key from my pocket into its keyhole, but the thing would not budge.

'It's no good,' I said. 'He wouldn't leave anything he valued in a place like this. That sort of fellow doesn't take risks. If he wanted to hide something there are a hundred holes in this Chateau which would puzzle the best detective.'

'Can't you open it?' she asked. 'I've a fancy about that table. He was sitting here this afternoon and he may be coming back.'

I solved the problem by turning up the escritoire and putting my knee through the cupboard door. Out of it tumbled a little dark-green attache case.

'This is getting solemn,' said Mary. 'Is it locked?'

It was, but I took my knife and cut the lock out and spilled the contents on the table. There were some papers, a newspaper or two, and a small bag tied with black cord. The last I opened, while Mary looked over my shoulder. It contained a fine yellowish powder.

'Stand back,' I said harshly. 'For G.o.d's sake, stand back and don't breathe.'

With trembling hands I tied up the bag again, rolled it in a newspaper, and stuffed it into my pocket. For I remembered a day near Peronne when a Boche plane had come over in the night and had dropped little bags like this. Happily they were all collected, and the men who found them were wise and took them off to the nearest laboratory. They proved to be full of anthrax germs ...

I remembered how Eaucourt Sainte-Anne stood at the junction of a dozen roads where all day long troops pa.s.sed to and from the lines. From such a vantage ground an enemy could wreck the health of an army ...

I remembered the woman I had seen in the courtyard of this house in the foggy dusk, and I knew now why she had worn a gas-mask.

This discovery gave me a horrid shock. I was brought down with a crash from my high sentiment to something earthly and devilish. I was fairly well used to Boche filthiness, but this seemed too grim a piece of the utterly d.a.m.nable. I wanted to have Ivery by the throat and force the stuff into his body, and watch him decay slowly into the horror he had contrived for honest men.

'Let's get out of this infernal place,' I said.

But Mary was not listening. She had picked up one of the newspapers and was gloating over it. I looked and saw that it was open at an advertis.e.m.e.nt of Weissmann's 'Deep-breathing' system.

'Oh, look, d.i.c.k,' she cried breathlessly.

The column of type had little dots made by a red pencil below certain words.

'It's it,' she whispered, 'it's the cipher-I'm almost sure it's the cipher!'

'Well, he'd be likely to know it if anyone did.'

'But don't you see it's the cipher which Chelius uses-the man in Switzerland? Oh, I can't explain now, for it's very long, but I think-I think-I have found out what we have all been wanting. Chelius ...'

'Whisht!' I said. 'What's that?'

There was a queer sound from the out-of-doors as if a sudden wind had risen in the still night.

'It's only a car on the main road,' said Mary.

'How did you get in?' I asked.

'By the broken window in the next room. I cycled out here one morning, and walked round the place and found the broken catch.'

'Perhaps it is left open on purpose. That may be the way M. Bommaerts visits his country home ... Let's get off, Mary, for this place has a curse on it. It deserves fire from heaven.'

I slipped the contents of the attache case into my pockets. 'I'm going to drive you back,' I said. 'I've got a car out there.'

'Then you must take my bicycle and my servant too. He's an old friend of yours-one Andrew Amos.'

'Now how on earth did Andrew get over here?'

'He's one of us,' said Mary, laughing at my surprise. 'A most useful member of our party, at present disguised as an infirmier in Lady Manorwater's Hospital at Douvecourt. He is learning French, and ...'

'Hush!' I whispered. 'There's someone in the next room.'

I swept her behind a stack of furniture, with my eyes glued on a crack of light below the door. The handle turned and the shadows raced before a big electric lamp of the kind they have in stables. I could not see the bearer, but I guessed it was the old woman.

There was a man behind her. A brisk step sounded on the parquet, and a figure brushed past her. It wore the horizon-blue of a French officer, very smart, with those French riding-boots that show the shape of the leg, and a handsome fur-lined pelisse. I would have called him a young man, not more than thirty-five. The face was brown and clean-shaven, the eyes bright and masterful ... Yet he did not deceive me. I had not boasted idly to Sir Walter when I said that there was one man alive who could never again be mistaken by me.

I had my hand on my pistol, as I motioned Mary farther back into the shadows. For a second I was about to shoot. I had a perfect mark and could have put a bullet through his brain with utter cert.i.tude. I think if I had been alone I might have fired. Perhaps not. Anyhow now I could not do it. It seemed like potting at a sitting rabbit. I was obliged, though he was my worst enemy, to give him a chance, while all the while my sober senses kept calling me a fool.

I stepped into the light.

'Hullo, Mr Ivery,' I said. 'This is an odd place to meet again!'

In his amazement he fell back a step, while his hungry eyes took in my face. There was no mistake about the recognition. I saw something I had seen once before in him, and that was fear. Out went the light and he sprang for the door.

I fired in the dark, but the shot must have been too high. In the same instant I heard him slip on the smooth parquet and the tinkle of gla.s.s as the broken window swung open. Hastily I reflected that his car must be at the moat end of the terrace, and that therefore to reach it he must pa.s.s outside this very room. Seizing the damaged escritoire, I used it as a ram, and charged the window nearest me. The panes and shutters went with a crash, for I had driven the thing out of its rotten frame. The next second I was on the moonlit snow.

I got a shot at him as he went over the terrace, and again I went wide. I never was at my best with a pistol. Still I reckoned I had got him, for the car which was waiting below must come back by the moat to reach the highroad. But I had forgotten the great closed park gates. Somehow or other they must have been opened, for as soon as the car started it headed straight for the grand avenue. I tried a couple of long-range shots after it, and one must have damaged either Ivery or his chauffeur, for there came back a cry of pain.

I turned in deep chagrin to find Mary beside me. She was bubbling with laughter.

'Were you ever a cinema actor, d.i.c.k? The last two minutes have been a really high-cla.s.s performance. "Featuring Mary Lamington." How does the jargon go?'

'I could have got him when he first entered,' I said ruefully.

'I know,' she said in a graver tone. 'Only of course you couldn't ... Besides, Mr Blenkiron doesn't want it-yet.'

She put her hand on my arm. 'Don't worry about it. It wasn't written it should happen that way. It would have been too easy. We have a long road to travel yet before we clip the wings of the Wild Birds.'

'Look,' I cried. 'The fire from heaven!'

Red tongues of flame were shooting up from the out-buildings at the farther end, the place where I had first seen the woman. Some agreed plan must have been acted on, and Ivery was destroying all traces of his infamous yellow powder. Even now the concierge with her odds and ends of belongings would be slipping out to some refuge in the village.

In the still dry night the flames rose, for the place must have been made ready for a rapid burning. As I hurried Mary round the moat I could see that part of the main building had caught fire. The hamlet was awakened, and before we reached the corner of the highroad sleepy British soldiers were hurrying towards the scene, and the Town Major was mustering the fire brigade. I knew that Ivery had laid his plans well, and that they hadn't a chance-that long before dawn the Chateau of Eaucourt Sainte-Anne would be a heap of ashes and that in a day or two the lawyers of the aged Marquise at Biarritz would be wrangling with the insurance company.

At the corner stood Amos beside two bicycles, solid as a graven image. He recognized me with a gap-toothed grin.

'It's a cauld night, General, but the home fires keep burnin'. I havena seen such a cheery lowe since d.i.c.kson's mill at Gawly.'