The morning of the third day after the failure of the search, and of the sixth since McCarthy's disappearance, had arrived. During that time Percy Darrow, apparently insensible to fatigue, had maintained an almost sleepless vigil. His meals Jack Warford brought in to him; he dozed in his chair or on the couch. Never did he appear to do anything.

The very persistent quietude of the man ended by making its impression. To all questions, however, Darrow returned but the one reply, delivered always in a voice full of raillery:

"I couldn't bear to miss a single step of Eldridge's masterly work."

About half past nine of the morning in question, through the door to the wireless office, always half opened, somebody looked hesitatingly into the room. Instantly Darrow and Jack were on their feet and in the hallway.

"Helen!" cried Jack.

"What is it? Anything happened?" demanded Darrow.

She surveyed them both amusedly.

"You certainly look like a frowzy tramp, Jack," she told her brother judiciously, "and you need sleep," she informed Darrow.

The young scientist bowed ironically, his long lashes drooping over his eyes in his accustomed lazy fashion as he realized that the occasion was not urgent. Helen turned directly to him.

"When are you going to stop this?" she demanded.

Darrow raised his eyebrows.

"You needn't look at me like that. You said you could lay your hands on Monsieur X at any moment; why don't you do it?"

"Eldridge is too amusing."

"Too amusing!" echoed the girl. "All you think of is yourself."

"Is it?" drawled Darrow.

"Have you been out in the city? Have you seen the people? Have you seen men out of work? Families leaving their homes? Panic spreading slowly but surely over a whole city?"

"Those pleasures have been denied me," said Darrow blandly.

The girl looked at him with bright angry eyes. Her cheeks were glowing, and her whole figure expressed a tense vibrant life in singular contrast to the apparent indolence of the men at whom she was talking.

"You are insufferable!" She fairly stamped her foot in vexation. "You are an egoist! You would play with the welfare of four million people to gratify your little personal desire for getting even!"

"Steady, sis!" warned Jack.

Darrow had straightened, and his indolent manner had fallen from him.

"I have said............