She looked down at her hands, resting on the desk in front of her. They were shaking. She felt that her insides were shaking, too.

Eat a good meal and get some rest? That was a joke. The way she was feeling, if she tried to eat she would choke on the first bite. Sleep was out of the question.

She was too agitated even to sit still. Her rooms, usually comfortably modest and cozy, now had walls that seemed to crowd in on her. The old Durer and Escher prints that she had brought in from Argus Station and hung with pleasure irritated rather than satisfied. She recalled what Hannah Krauss had said, soon after Milly arrived at Jovian L-4. The occupational hazards of mathematicians, logicians, and crypt-analysts were depression, insanity, paranoia, and suicide.

Depression was something she had fought off as a teenager. The solution in those years had been not rest, but physical activity and a change of mental focus.

Milly slipped into her exercise suit and headed for the nearest free-speed access point. She walked fast, posing a practical problem for herself as she went. Last night had started in her cubicle at the Puzzle Network’s Command Center in Sector 291, deep down on Level 147. It had ended in the research quarantine facility, up close to the surface on Level 4, in Sector 82. Today’s meeting with Bat would logically be held in one of those locations. Milly wanted an exercise route that would allow her to reach either of them quickly.

Most people would have consulted a General Route Planner, providing optimal routes between any pair of Levels and Sectors within Ganymede. Milly didn’t want to do that. She needed a distraction. She entered the free-speed system and began to jog along it, passing or being passed by scores of others running for exercise or pleasure. As she went she visualized and held in her mind the intersecting network of vertical and horizontal routes to which the free-speed course had access. When the call came, she needed to be able to move from her location of the moment to wherever Bat was holding the meeting.

She ran steadily for an hour, feeling the tension inside her gradually fade. Her brain was well into the pleasant endorphin-soothed state induced by exercise when, annoyingly, her receiver buzzed for attention.

“Yes?”

The voice in her ear was not that of Bat, or Alex Ligon, or anyone else whom she recognized. It said, “Interested parties should convene at the Ligon Industries’ Experimental Center, Level twenty-two, Sector one-one-eight.”

Milly swore to herself. The meeting was going to take place at neither of the locations for which she had planned rapid routing. She had never before been to the Ligon Industries’ Experimental Center; she had, in fact, never heard of it.

She sprinted for the next exit on the free-speed course and ran through the output chamber. You were not supposed to do that, and the output processor did not have enough time to finish its job. Milly emerged with perspiration removed from her body and clothing, but her core temperature was still well above normal. As she called on the General Route Planner and asked it to take her to Level 22, Sector 118, she could feel new sweat breaking out on her body.

When she arrived at the Experimental Center it was clear that sweat was not going to be an immediate issue. The admitting Level Two Fax was having a major fight — as much as a Fax was permitted to fight — with somebody else.

“It’s not Ms. Bloom, you electronic slop of Brownian motion.” The woman arguing with the Fax was thin, red-haired, and extremely angry. “I’ve told you ten times, it’s Dr. Bloom. And if Ligon Industries can invade my lab in the middle of the night, without permission, I’m damned if you’ll keep me out of theirs. Let me in.”

“I am sorry, Ms. Bloom, but there is no authorization for your admission.”

“That’s it! Go away. Get lost. I request a Level Five Fax.”

“Very well, Ms. Bloom.”

Milly stepped forward. “Dr. Bloom? My name is Milly Wu. I was one of the people who went into your facility last night.”

The woman turned to her. “Were you now? Who said you could?”

“No one. But I may be able to help.” Milly turned to the Fax, which was wavering in outline during the attempted invocation of a Level Five version. Currently it had the form of a person of uncertain age and gender. “My name is Milly Wu. I believe that I have authorization to attend this meeting.”

The image solidified. “That is correct, Ms. Wu. You may enter.” The double doors beyond the Fax were opening.

“I have with me my associate, Dr.—” Milly turned to the other woman.

“Bloom. Dr. Valnia Bloom.”

“My associate, Dr. Valnia Bloom. We are both attending this meeting. We both require admission.”

“Very good.” The Fax nodded. “I will announce your arrival and forward your names. Milly Wu and Dr. Valnia Bloom. Follow the wall indicators.”

They walked forward together. As they passed through the double doors, Valnia Bloom said, “Thank you, I suppose. But I want to know what the hell was going on last night. Upon my return to my lab I discovered that I had been accused of the unauthorized use of a Mayfly-class ship and of a Flyboy scooter. The Mayfly has been lost, and the scooter with its two passengers was picked up by a medical ship following an emergency call. The captain of the OSL Achilles called, asking what I had done with his first officer. I learned that there have been unauthorized entries and exits to my facility. Worst of all, a man in my care died — and I have yet to be offered a shred of explanation as to what was going on. It required a major effort on my part even to learn of the existence of this meeting.”

“Dr. Bloom, I wish I had answers, but I don’t. We were promised some today. That’s why I came here.”

“We’d better get some. Or you can look for blood on the carpet.”

There was no carpet, only the tough corrosion-resistant flooring of a scientific lab, but Milly got the message. Valnia Bloom was where Milly herself had been two hours ago, all set to blow her main circuits.

When something was ready to explode, you stayed out of the way. Milly trailed Valnia Bloom as they followed the lighted wall strips, along a corridor, through another pair of double doors, and into a long chamber filled with scientific equipment, none of which Milly recognized.

She did, however, recognize the group of people at the far end. Alex Ligon, her companion for last night’s illegal breaking and entry, was there. The woman, Magrit Knudsen, whom Alex had identified as his boss and as a very senior member of the Ganymede cabinet, was present. So was Bengt Suomi, looking like the devil with his dark eyebrows and brooding saturnine face. Finally there was the Great Bat, towering over everyone and peering at a complicated device sitting on top of a work bench.

Any concern that Milly had over personal freshness disappeared. Bat was wearing the same funereal black garb as last night, and he had clearly slept in it or worse. He turned as they approached. He gave Milly only a brief nod of recognition, but her companion received his full attention.

“Dr. Bloom?”

“Right.” Valnia Bloom was staring. “I’ve seen you before, or at least your picture. Weren’t you involved a few years ago in explorations on Europa?”

“That could be described as correct. My name is Rustum Battachariya. I owe you a sincere apology. We invaded your research facility last night, without asking.”

“Did you try to ask? I’m not hard to reach.”

“We did not. There were, however, extenuating circumstances. We believed at the time that rapid action was needed to forestall an unimaginable disaster. We were wrong, for reasons I still do hot understand, but the basis for our concern will soon become clear to you. First, however, I would like to preface a demonstration with a statement. And if it at first appears to be a digression, please bear with me.”