“Young lady for Mr. Humboldt, Fred. I’ll let them know she’s here if you’ll take her on up.”

Fred unlocked the door-no remote-control clicks here-and took me to the elevator at a stately tread. I followed him into a roomy cage with a floral carpet on the floor and a plush-upholstered bench against the back wall. I sat casually on the bench, crossing my legs, as though personal elevator service were an everyday occurrence with me.

The elevator opened onto what might have been the foyer of a mansion. Gray-white marble tiles showing streaks of pink were covered here and there by throw rugs that had probably been made in Persia when the Ayatollah’s grandfather was a baby. The hall seemed to form an atrium, with the elevator at its center, but before I could tiptoe down to a marble statue in the left corner to explore, the carved wooden door in front of me opened.

An old man stood there in morning dress. His scalp showed pink through wisps of fine white hair. He inclined his head briefly, a token bow, but his blue eyes were frosty and remote. Rising to the solemnity of the occasion, I fished in my bag and handed him a card without speaking.

“Very good, miss. Mr. Humboldt will see you now. If you’ll follow me…”

He walked slowly, either from age or from some concept of a butler’s proper gait, giving me time to gawk in what I trusted was a discreet fashion. About halfway along the length of the building he opened a door on the left and held it for me to enter. Looking at the books lining three walls and the opulent red-leather furniture in front of a fireplace in the fourth, my keen intuition told me we were in the library. A florid man, heavy without being corpulent, sat in front of the fire with a newspaper. As the door opened he put the paper down and got to his feet.

“Ms. Warshawski. How good of you to come on such short notice.” He held out a firm hand.

“Not at all, Mr. Humboldt.”

He motioned me to a leather armchair on the other side of the fire from him. I knew from the Who’s Who entry that he was eighty-four, but he could have said sixty without anyone raising an eyebrow. His thick hair still showed a touch of pale yellow, and his blue eyes were sharp and clear in a face almost free of wrinkles.

“Anton, bring us some cognac-you drink cognac, Ms. Warshawski?-and then we’ll be fine on our own.”

The butler disappeared for perhaps two minutes, during which my host courteously made sure the fire wasn’t too hot for me. Anton returned with a decanter and snifters, poured, carefully placed the decanter in the center of a small table at Humboldt’s right hand, fiddled with the fire tongs. I realized he was as curious as I about what Humboldt wanted and was trying to think of ways to linger, but Humboldt dismissed him briskly.

“Ms. Warshawski, I have an awkward matter to discuss, and I beg your indulgence if I don’t do so with maximum grace. I’m an industrialist, after all, an engineer more at home with chemicals than beautiful young women.” He had come to America as a grown man; even after close to sixty years a mild accent remained.

I smiled sardonically. When the owner of a ten-billion-dollar empire starts apologizing for his style, it’s time to hold tightly to your purse and count all your fingers.

“I’m sure you underestimate yourself, sir.”

He gave me a quick, sidelong glance and decided that warranted a barking laugh. “I see you are a careful woman, Ms. Warshawski.”

I sipped the cognac. It was staggeringly smooth. Please let him call me for frequent consultations, I begged the golden liquid. “I can be reckless when I have to, Mr. Humboldt.”

“Good. That’s very good. So you’re a private investigator. And do you find it a job that allows you to be both careful and reckless?”

“I like being my own boss. And I don’t have the desire to do it on the scale you’ve achieved.”

“Your clients speak very highly of you. I was talking to Gordon Firth just today and he mentioned how grateful the Ajax board was for your efforts there.”

“I’m delighted to hear it,” I said, sinking back in the chair and sipping some more.

“Gordon does a lot of my insurance, of course.”

Of course. Gustav calls Gordon and tells him he needs a thousand tons of insurance and Gordon says sure and thirty young men and women work eighty-hour weeks for a month putting it all together and then the two shake hands genially at the Standard Club and thank each other for their trouble.

“So I thought I might be able to help you out with one of your inquiries. After listening to Gordon’s glowing report I knew you were intelligent and discreet and not likely to abuse information given you in confidence.”

With enormous effort I kept myself from bolting up in the chair and spilling cognac all over my skirt. “It’s hard for me to imagine where our spheres of activity intersect, sir. By the way, this is most excellent cognac. It’s like drinking a fine single malt.”

At that Humboldt roared with genuine laughter. “Beautiful, my dear Ms. Warshawski. Beautiful. To take my news so calmly and then praise my liquor with the most subtle of insults! I wish I could persuade you to cease being your own boss.”

I smiled and put the snifter down. “I love compliments as much as the next person, and it’s been a tough day-I can use them. But I’m beginning to wonder who is meant to be helping whom. Not that it wouldn’t be a privilege to be of service to you.”

He nodded. “I think we can be of service to each other. You asked where our spheres of activity intersect-a fine expression. And the answer lies in South Chicago.”

I thought for a minute. Of course. I should have known. Xerxes had to be part of Humboldt Chemical. It was just being so used to thinking of it as part of my childhood’s landscape that I hadn’t made the connection when Anton phoned.

I casually mentioned it and Humboldt nodded again. “Very good, Ms. Warshawski. The chemical industry made a great contribution to the war effort. The Second World War I’m talking about, of course. And the war effort in turn prompted research and development on a grand scale. Many of the products that all of us-I mean Dow, Ciba, Imperial Chemical, all of us-make our bread and butter on today can be traced to research we did then. Xerxine was one of Humboldt’s great discoveries, one of the 1, 2 dichlorethanes. The last one I was able to devote time to myself.”

He stopped himself with a turned-up hand. “You’re not a chemist. That won’t be of interest to you. But we called the product Xerxes, because of the Xerxine, of course, and opened the South Chicago plant in 1949. My wife was an artist. She designed the logo, the crown on the purple background.”

He stopped to offer me the decanter. I didn’t want to appear greedy. On the other hand, to refuse might have seemed rude.

“Well, that South Chicago plant was the start of Humboldt’s international expansion, and it’s always meant a great deal to me. So even though I no longer concern myself with the day-to-day running of the company-I have grandchildren, Ms. Warshawski, and an old man fancies himself reliving his youth with young children. But my people know I care about that plant. So when a beautiful young detective begins poking around, asking questions, they naturally tell me.”

I shook my head. “I’m sorry if they needlessly alarmed you, sir. I’m not poking around in the plant. Merely trying to trace some men as part of a personal inquiry. For some reason your Mr. Joiner-the personnel manager-wanted me to believe they never worked for you.”

“So you found Dr. Chigwell.” His deep voice had sunk to a rumbling murmur, difficult to make out.

“Who was even more electrified by my questions than young Joiner. I couldn’t help wondering if he had a personal agenda of his own. Some transactions of his youth that weigh on his old-age conscience.”