"Come in," he growled. "You are much too early. Why didn't you give the sign, or did you think I would not open if you did?"
Still grumbling, and with his face averted, von Secker shuffled across the room to a table on which were spread several sheets of drawing paper and tracing cloth.
"You are still too early," he continued. "I suppose you are here again concerning the plans?"
"I am, Karl von Secker," said Athol sternly, at the same time covering the spy with his revolver.
The effect of the words, spoken in English, was electrical. In an instant the German's lassitude dropped from him like a shedded garment. Seizing a lead paper-weight from the table he poised it to hurl at the lad's head.
Athol hesitated. Not that he was lost, but because he was confronted with a tricky problem. Setting aside the compunction he felt at shooting down a man, even though he were a dangerous spy, he realised that the house would be alarmed at the report of the weapon. He was out to regain possession of the battleplane's plans, not to get himself arrested by the Dutch authorities on a charge of murder.
It was as if von Secker read his thoughts, for the spy, scowling and grinding his teeth, made no further attempt to hurl the lump of metal. He, too, did not wish to be embroiled with the officials of a neutral government, although here was a good chance of making his escape across the frontier.
Athol lowered his revolver. Von Secker replaced the paper weight, although he still kept his fingers in contact with it.
"You have come on a fool's errand, young man," snarled the spy.
Athol, regretting that he had not discarded his clumsy wooden shoes, looked his antagonist straight in the face.