Challis hitched his cuffs back from his wrists. His eyesight was very keen. He had seen the man's face and recognised it. It was the face of Fritz Seligmann, the German spy!
With the stealthy softness of a cat stalking its prey, the policeman crept forward, and, just as Seligmann had raised his hand to turn out the second light, leapt upon him, gripping him from behind by the two arms.
There was a heavy gasp from the astonished German as he went down on his knees, the policeman's weight on top of him. He writhed and struggled to free himself, and succeeded in getting his right hand to his hip pocket, from which, with an effort, he drew his loaded revolver.
Challis guessed rather than knew what was in the man's hand. In an instant he had seized the German's wrist, twisted the hand under it, and secured the weapon from the helpless fingers.
"Now," he said, speaking for the first time, "I think I've got you. If you move I'm goin' to use this here pistol. You're an enemy, and you may take it from me I don't care if I shoot you dead here and now no more than if I killed you on the field of battle."
Seligmann was lying with his face to the grass, panting, writhing, heaving under the weight of the constable's knee planted in the small of his back, while the cold ring of the revolver muzzle was pressed against the bone behind his ear and the policeman's forefinger was twitching at the trigger.
Thus they remained for some minutes, the one utterly helpless, the other resolute, alert, and astonishingly strong.
In those tense minutes Challis wondered what he was going to do. He did not want to use the revolver as anything else than a menace, and yet he knew that if he should move there would be a struggle, during which, by some trick or dexterity, his captive might escape.
In the back pocket of his overcoat was a pair of handcuffs. But how could he get hold of them without dropping the revolver? How could he hope to fix them on the German's wrists?
But if he could not get at the handcuffs, at least he could summon help. There were houses within call. The nearest was Sunnydene, for which Seligmann had no doubt been shaping; the next was Green Croft, then Major Redisham's. He managed to draw out his whistle, while his captive straggled more desperately than ever to get free. Just as he raised the whistle to his lips, he heard the quick patter of feet along the road. He blew a long, shrill blast.