Bigman said, "First, Dr. Cook, how did Urteil come to know the route Lucky and I were taking in the mines?"
Cook reddened. "I didn't know he knew the route."
"He didn't follow us directly. He took a parallel route as though he were intending to catch up and fall behind us well within the mines, after we had convinced ourselves that we were alone and unfollowed. To do that, he would have to be certain of the route we were planning to take. Now Lucky and I planned that route with you and with no one else. Lucky didn't tell Urteil and neither did I. Who did?"
Cook looked wildly about as though for help. "I don't know."
"Isn't it obvious you did?"
''No. Maybe he overheard."
"He couldn't overhear marks on a map, Dr. Cook.
… Let's pass on, now. I fought Urteil, and if gravity had stayed at Mercurian normal, he would still be alive. But it didn't stay there. It was suddenly hopped up to Earth-levels at just the moment where it helped to kill him. Who did that?"
"I don't know."
"You were the first one at Urteil's side. What were you doing? Making sure he was dead?"
"I resent that. Dr. Peverale… " Cook turned a flaming face toward his chief.
Dr. Peverale said with agitation, "Are you accusing Dr. Cook of having murdered Urteil?"
Bigman said, "Look. The sudden change in gravity pulled me to the ground. When I got to my feet, everyone else was either getting to their feet, too, or was still on the ground. When 75 to 150 pounds fall on your back without warning, you don't get to your feet in a hurry. But Cook had. He was not only on his feet, he had gotten to Urteil's side and was bending over him."
"What does that prove?" demanded Cook.
"It proves you didn't go down when the gravity went up, or you couldn't have gotten there in time. And why didn't you go down when the gravity went up? Because you expected it to go up and were braced for it. And why did you expect it to go up? Because you tripped the lever."
Cook turned to Dr. Peverale. "This is persecution. It's madness."
But Dr. Peverale looked at his second in stricken horror.
Bigman said, "Let me reconstruct the business. Cook was working with Urteil. That's the only way Urteil could have learned our route in the mines. But he was working with Urteil out of fear. Maybe Urteil was blackmailing him. Anyway, the only way Cook could get out from under was to kill Urteil. When I said I could murder the cobber if we fought under low gravity. I must have put an idea into his head, and when we had the fight he stood there waiting at the lever. That's all."
"Wait," cried Cook urgently, almost choked, "this is all-this is all… "
"You don't have to go by me," said Bigman. "If my theory is right, and I'm sure it is, then Urteil must have something in writing or on recording or on film that he can hold over Cook's head. Otherwise, Cook wouldn't have felt trapped to the point of murder. So search Urteil's effects. You'll find something and that will be it."
"I agree with Bigman," said Lucky.
Dr. Peverale said in bewilderment, "I suppose it's the only way of settling the matter, though how… "
And the air seemed to go out of Dr. Hanley Cook, leaving him pale, shaken, and helpless. "Wait," he said weakly, "I'll explain."
And all faces turned toward him.
Hanley Cook's lean cheeks were bathed in perspiration. His hands as he raised them, almost in supplication, trembled badly. He said, "Urteil came to me shortly after he arrived on Mercury. He said he was investigating the Observatory. He said Senator Swen-son had evidence of inefficiency and waste. He said it was obvious that Dr. Peverale ought to be retired; that he was an old man and incapable of bearing up under the responsibility. He said I might make a logical replacement."
Dr. Peverale, who listened to this with an air of stunned surprise, cried out. "Cook!"
"I agreed with him," said Cook sullenly. " You are too old. I'm running the place anyway while you occupy yourself with your Sirius mania." He turned again to Lucky. "Urteil said that if I helped him in his investigation he would see to it that I would be the next director. I believed him; everyone knows Senator Swenson is a powerful man.
"I gave him a great deal of information. Some of it was in writing and signed. He said he needed it for legal proceedings afterward.
"And then-and then he began holding that written information over my head. It turned out that he was a lot more interested in Project Light and the Council of Science. He wanted me to use my position to become a kind of personal spy for him. He made it quite plain that he would go to Dr. Peverale with evidence of what I had done if I refused. That would have meant the end of my career, of everything.
"I had to spy for him. I had to give information concerning the route Starr and Bigman were to take in the mines. I kept him up to date on everything Mindes did. Every time I surrendered a bit more to him I was more helplessly in his power. And after a while I knew that someday he would break me, no matter how much I helped him. He was that kind of man. I began to feel that the only way I could escape was to kill him. If only I knew how--
"Then Bigman came to me with his plan to fight Urteil under low gravity. He was so confident that he could toss Urteil about. I thought then I might…
The chances would be one in a hundred, maybe one in a thousand, but I thought, what was there to lose? So I stood at the pseudo-grav controls and waited my chance. It came and Urteil died. It worked perfectly. I thought it would go down as accident. Even if Big-man were in trouble, then the Council could get him out of it. No one would be hurt except Urteil, and he deserved it a hundred times over. Anyway, that's it." In the awed silence that followed, Dr. Peverale said huskily, "Under the circumstances, Cook, you will of course consider yourself relieved of all duty and under air…"
"Hey, hold it, hold it," cried Bigman. "The confession isn't complete yet. Look here, Cook, that was the second time you tried to kill Urteil, wasn't it?"
"The second time?" Cook's tragic eyes lifted.
"What about the gimmicked inso-suit? Urteil said for us to watch out for one, so he must have had experience with it. He made out Mindes was doing it, but that Urteil was a lying cobber and nothing he says has to be believed. What I say is that you tried to kill Urteil that way, but he caught the suit and forced you to transfer it to our room when we came. Then he warned us about it just to get us thinking he was on our side and make trouble for Mindes. Isn't that so?"
"No," shouted Cook. "No! I had nothing to do with that inso-suit. Nothing."
"Come on," began Bigman. "We're not going to believe:… "
But now Lucky Starr got to his feet. "It's all right, Bigman. Cook had nothing to do with the inso-suit.
You can believe him. The man responsible for the slashed inso-suit is the man responsible for the robot."
Bigman stared at his tall friend incredulously. "You mean the Sirians, Lucky?"
"No Sirians," said Lucky. "There are no Sirians on Mercury. There never have been."
16. Results of the Trial
"Perfectly." Lucky Starr moved up to Dr. Peverale's desk, sat down on one corner of it, and faced the assemblage. "Dr. Peverale will bear me out on that, I'm sure, when I've explained the reasoning."
"I'll bear you out? No fear of that, I assure you," huffed the old astronomer, his face set in an attitude of bitter disapproval. "It is scarcely worth discussing… By the way, we'll have to place Cook under arrest." He half rose.
Lucky urged him gently back into his seat. "It's all right, sir. Bigman will make sure that Cook will remain under control."
"I won't make any trouble," said the despairing Cook in a muffled tone. Bigman pulled his armchair close to Cook's nevertheless.