Mike watched everyone at the table. No one moved.

"So the killer, realizing that he had failed twice, decided to do the job himself. First, he went into the low-power room and slugged the man on duty. He intended to kill him, but he didn"t hit hard enough. When that man wakes up, he"ll be able to testify against the killer.

"Then the killer ordered Snook.u.ms to tear out the switches. He had made sure that Snook.u.ms would be waiting outside. Before he called Snook.u.ms in, of course, he had to put the duty man in a tool closet, so that the robot wouldn"t see him. He told Snook.u.ms to wait five minutes and then smash the switches and head back to his cubicle.

"Then the killer went to my room and waited. When the lights went out and the door opened, he intended to go in and smash my skull, making it look as though either Mellon or Snook.u.ms had done it.

"But he didn"t figure on my awakening as soon as the switches were broken. He heard me moving around and decided to wait until I came out.

"But I heard him breathing. It was quite faint, and I wouldn"t have heard it, except for the fact that the air conditioners were off. Even so, I couldn"t be sure.

"However, I knew it wasn"t Snook.u.ms. Snook.u.ms radiates a devil of a lot more heat than a human being, and besides he smells of machine oil.

"So I pulled my little trick with the boots. The killer waited and waited for me to come out, and I was already out. Then Chief Multhaus approached from the other direction. The killer knew he"d have to get out of there, so he went in the opposite direction. He met Snook.u.ms, who was still obeying orders. Snook.u.ms smacked into me on his way down the hall.

"He could do that, you see, because I was an angel. If he hurt me of his own accord, I couldn"t take revenge on anyone but him. And there was no necessity to obey my orders, either, since he was obeying the orders of the killer, which held precedence.

"Then, to further confuse things, the killer went to Mellon"s room. The physician was in a drugged stupor, so the killer carried him out and put him in an unlikely place, so that we"d think that perhaps Mellon had been the one who"d tried to get me."

He had everyone"s eyes on him now. They didn"t want to look at each other.

Pete Jeffers said: "Mike, if Mellon was poisoned, like you say, how come he was able to attack Mister Vaneski?"

"Ah, but did he? Think back, Pete. Mellon--dying or already dead--had been propped upright in that narrow locker. When it was opened, he started to _fall_ out--straight toward the man who had opened the locker, naturally. Vaneski jumped back and shot before Mellon even hit the floor. Isn"t that right?"

"Sure, sure," Jeffers said slowly. "I reckon I"d"ve done the same thing if he"d started to fall out toward me. I wasn"t even lookin" when the locker was opened. I didn"t turn around until that stun gun went off--then I saw Mellon falling."

"Exactly. No matter how it may have looked, Vaneski couldn"t have killed him with the stun gun, because he was already either dead or so close to death as makes no difference."

Ensign Vaneski rather timidly raised his hand. "Excuse me, sir, but you said this killer was waiting for you outside your room when the lights went out. You said you knew it wasn"t Snook.u.ms because Snook.u.ms smells of hot machine oil, and you didn"t smell any. Isn"t it possible that an air current or something blew the smell away? Or--"

Mike shook his head. "Impossible, Mister Vaneski. I woke up when the door slid open. I heard the last dying whisper of the air conditioners when the power was cut. Now, we know that Snook.u.ms tore out those switches. He"s admitted it. And the evidence shows that a pair of waldo hands smashed those switches. Now--_how could Snook.u.ms have been at my door within two seconds after tearing out those switches_?

"He couldn"t have. It wasn"t Snook.u.ms at my door--it was someone else."

Again they were all silent, but the question was on their faces: Who?

"Now we come to the question of motive," Mike continued. "Who among you would have any reason to kill me?

"Of the whole group here, I had known only Captain Quill and Commander Jeffers before landing in Antarctica. I couldn"t think of any reason for either of them to want to murder me. On the other hand, I couldn"t think of anything I had done since I had met the rest of you that would make me a target for death." He paused. "Except for one thing." He looked at Jakob von Liegnitz.

"How about it, Jake?" he said. "Would you kill a man for jealousy?"

"Possibly," said von Liegnitz coldly. "I might find it in my heart to feel very unkindly toward a man who made advances toward my wife. But I have no wife, nor any desire for one. Miss Crannon"--he glanced at Leda--"is a very beautiful woman--but I am not in love with her. I am afraid I cannot oblige you with a motive, Commander--either for killing Lieutenant Mellon or yourself."

"I thought not," Mike said. "Your statement alone, of course, wouldn"t make it true. But we have already shown that the killer had to be on good terms with Mellon in order to borrow his books and slip a drug into his wine. He would have to be a visitor in Mellon"s quarters. And, considering the strained relations between the two of you, I think that lets you out, Jake."

Von Liegnitz nodded his thanks without changing his expression.

"But there was one thing that marked these attempts. I"m sure that all but one of you has noticed it. They are incredibly, childishly sloppy."

Mike paused to let that sink in before he went on. "I don"t mean that the little details weren"t ingenious--they were. But the killer never stopped to figure out the ultimate end-point of his schemes. He worked like the very devil to convince Snook.u.ms that it would be all right to kill me without ever once considering whether Snook.u.ms would do it or not. He then drugged Mellon"s wine, not knowing whether Mellon would try to kill me or someone else--or anyone at all, for that matter. He got a dream in his head and then started the preliminary steps going without filling in the necessary steps in between. Our killer--no matter what his chronological age--does _not_ think like an adult.

"And yet his hatred of me was so great that he took the chances he has taken, here on the _Brainchild_, where it should have been obvious that he stood a much better chance of being caught than if he had waited until we were back on Earth again.

"So I gave him one more chance. I handed him my life on a platter, you might say.

"He grabbed the bait. I now own a s.p.a.cesuit that would kill me very quickly if I went out into that howling, hydrogen-filled storm outside."

Then he looked straight at the killer.

"Tell me, Vaneski, are you in love with your half sister? Or is it your half brother?"

Ensign Vaneski had already jumped to his feet. The grimace of hate on his youthful face made him almost unrecognizable. His hand had gone into a pocket, and now he was leaping up and across the table, a singing vibroblade in his hand.

"_You son of a b.i.t.c.h! I"ll kill you, you son of a b.i.t.c.h!_"

Mike the Angel wasn"t wearing the little gadget that had saved his life in Old Harry"s shop. All he had were his hands and his agility. He slammed at the ensign"s wrist and missed. The boy was swooping underneath Mike"s guard. Mike spun to one side to avoid Vaneski"s dive and came down with a balled fist aimed at the ensign"s neck.

He almost hit Lieutenant Keku. The big Hawaiian had leaped to his feet and landed a hard punch on Vaneski"s nose. At the same time, Jeffers and von Liegnitz had jumped up and grabbed at Vaneski, who was between them.

Black Bart had simply stood up fast, drawn his stun gun, and fired at the young officer.

Ensign Vaneski collapsed on the table. He"d been slugged four times and hit with a stun beam in the s.p.a.ce of half a second. He looked, somehow, very young and very boyish and very innocent.

Dr. Fitzhugh, who had stood up during the brief altercation, sat down slowly and picked up his cup of coffee. But his eyes didn"t leave the unconscious man sprawled across the table. "How could you be so sure, Commander? About his actions, I mean. About his childishness."

"A lot of things. The way he played poker. The way he played bridge. He never took the unexpected into account."

"But why should he want to kill you here on the ship?" Fitzhugh asked.

"Why not wait until you got back to Earth, where he"d have a better chance?"

"I think he was afraid I already knew who he was--or would find out very quickly. Besides, he had already tried to kill me once, back on Earth."

Leda Crannon looked blank. "When was that, Mike?"

"In New York. Before I ever met him. I was responsible for the arrest of a teen-age brother and sister named Larchmont. The detective in the case told me that they had an older half brother--that their mother had been married before. But he didn"t mention the name, and I never thought to ask him.

"Very shortly after the Larchmont kids were arrested, Vaneski and another young punk climbed up into the tower of the cathedral across from my office and launched a cyanide-filled explosive rocket into my rooms. I was lucky to get away.

"The kid with Vaneski was shot by a police officer, but Vaneski got away--after knifing a priest with a vibroblade.

"It must have given him a h.e.l.l of a shock to report back to duty and find that I was going to be one of his superior officers.

"As soon as I linked things up in my own mind, I checked with Captain Quill. The boy"s records show the names of his half-siblings. They also show that he was on leave in New York just before being a.s.signed to the _Brainchild_. After that, it was just a matter of trapping him. And there he is."

Leda looked at the unconscious boy on the table.

"Immaturity," she said. "He just never grew up."