“What I ought to do, he thought, is take it like mathematics. Check back. Look for discrepancies. Things not included. Things not explained. Mistakes. Also, I should extrapolate. Imagine. He felt more detached, less frantic.

There were several elements not satisfactorily accounted for. Little things. Why, for example, had the warehouse in New York been empty? And what had there been about it that had impressed him as meaningful, but that he had never called to consciousness? He had the answer to that, abruptly. The floor of that vast building had glittered faintly with the mica-like brilliance of such broken stone as is excavated in Manhattan. He’d thought of it as coming in from the streets on truck wheels. Actually, it could have come from excavating in the building. And they wouldn’t have wanted things stored there if they had wanted to dig.

Before this instant, Duff realized, he had conceived of an assembled A-bomb as something in a huge case or a truck above ground. Why not bury it? The warehouse wasn’t far from Wall Street. An A-bomb going off there, even underground, would destroy the financial heart of New York City, of America.

That was one thing. He could tell Higgins to have them tear up the floor of the place.

Then, perhaps, they’d get tangible — and terrifying— evidence. That idea, a fresh idea, one in which he had confidence, excited him; his mind raced anew. But he saw the error of that. He had to think, not feel.

The second idea he evolved had to do with Harry Ellings’ history. It was odd, in a way. He’d been a letter carrier. Developed varicosis — he had said. He limped a little and complained of leg pains. True. That could have been put on. Why? Because, Duff reasoned, a bad leg might have been a first step in training for a new job. If Harry had belonged for years to a secret underground, the organization might have wanted him to be in a trucking company, where freight could be forwarded secretly.

It would be easier, Duff thought, and a great deal safer, to retrain an established underground member than to try to persuade some unknown mechanic to turn to treason. So, perhaps, Harry had feigned the bad leg, learned to be a mechanic and moved into Miami-Dade Terminal Trucking Company as part of a plan. That way Harry could retain his mask of ordinariness. The idea was strengthened, if not corroborated, by the existence of the quarry, the sinkhole and the connecting tunnel, and by Harry’s meeting with the huge man near the quarry.

That pattern, while logical, seemed not to lead any further toward Eleanor. It took Duff more than an hour — an hour of slow, relaxed new thought. He had been turning over in his mind all he knew about the man seven feet tall. He had actually seen the man twice: one evening in New York, one night with Harry Ellings. The FBI also had reports on the man.

Two different agents, on two different nights, had seen the man enter a place. But not come out. They’d lost him, both nights.

Why nights? Did he come out only at night, because of his great stature, as Higgins evidently believed? Or could it be that there was something about his immense size which wouldn’t look natural in daylight? Could size be a kind of truck? Itself a ruse? The figure, menacing, looming, weird, had obviously perturbed even the sanguine G-men. Was that intentional?