come into court without a psychoprobe record, we can't win. In a case as serious as murder, not to have used the psychoprobe is proof enough to the dumbest juror that the prosecution isn't sure of its ground.'
'Now what do you want of me?'
'Proof that he was on the Moon sometime in August. It's got to be done quickly. I can't hold him on suspicion much longer. And if news of the murder gets out, the world press will blow up like an asteroid striking Jupiter's atmosphere. A glamorous crime, you know-first murder on the Moon.'
'Exactly when was the murder committed?' asked Urth, in a sudden transition to brisk cross-examination.
'August twenty-seventh.'
'And the arrest was made when?'
'Yesterday, August thirtieth.'
'Then if Peyton were the murderer, he would have had time to return to Earth.'
'Barely. Just barely.' Davenport's lips thinned. 'If I had been a day sooner-If I had found his place empty-'
'And how long do you suppose the two, the murdered man and the murderer, were on the Moon altogether?' • 'Judging by the ground covered by the footprints, a number of days. A week, at the minimum.'
'Has the ship they used been located?'
'No, and it probably never will. About ten hours ago, the University of Denver reported a rise in background radioactivity beginning day before yesterday at 6 p.m. and persisting for a number of hours.
It's an easy thing. Dr. Urth, to set a ship's controls so as to allow it to blast off without crew and blow up, fifty miles high, in a micropile short.'
'If I had been Peyton,' said Dr. Urth thoughtfully, 'I would have killed the man on board ship and blown up corpse and ship together.'
'You don't know Peyton,' said Davenport grimly. 'He enjoys his victories over the law. He values them. Leaving the corpse on the Moon is his challenge to us.'
'I see.' Dr. Urth patted his stomach with a rotary motion and said, 'Well, there is a chance.' That you'll be able to prove he was on the Moon?'
That I'll be able to give you my opinion.'
'Now?'
The sooner the better. If, of course, I get a chance to interview Mr. Peyton.'
That can be arranged. I have a non-grav jet waiting. We can be in Washington in twenty minutes.'
But a look of the deepest alarm passed over the plump extraterrologist's face. He rose to his feet and pattered away from the T.B.I, agent toward the duskiest corner of the cluttered room.
'No!'
'What's wrong, Dr. Urth?'
'I won't use a non-grav jet. I don't believe in them.'
Davenport stared confusedly at Dr. Urth. He stammered, 'Would you prefer a monorail?'
Dr. Urth snapped, 'I mistrust all forms of transportation. I don't believe in them. Except walking. I don't mind walking.' He was suddenly eager. 'Couldn't you bring Mr. Peyton to this city, somewhere within walking distance? To City Hall, perhaps? I've often walked to City Hall.'
Davenport looked helplessly about the room. He looked at the myriad volumes of lore about the light-years. He could see through the open door into the room beyond, with its tokens of the worlds beyond the sky. And he looked at Dr. Urth, pale at the thought of non-grav jet, and shrugged his shoulders.
'I'll bring Peyton here. Right to this room. Will that satisfy you?' Dr. Urth puffed out his breath in a deep sigh. 'Quite.'
'I hope you can deliver, Dr. Urth.'
'I will do my best, Mr. Davenport.'
Louis Peyton stared with distaste at his surroundings and with contempt at the fat man who bobbed his head in greeting. He glanced at the seat offered him and brushed it with his hand before sitting down. Davenport took a seat next to him, with his blaster holster in clear view.
The fat man was smiling as he sat down and patted his round abdomen as though he had just finished a good meal and were intent on letting the world know about it.
He said, 'Good evening, Mr. Peyton. I am Dr. Wendell Urth, extraterrologist.' Peyton looked at him again, 'And what do you want with me?'
'I want to know if you were on the Moon at any time in the month of August.'
'I was not.'
'Yet no man saw you on Earth between the days of August first and August thirtieth.'
'I lived my normal life in August. I am never seen during that month. Let him tell you.' And he jerked his head in the direction of Davenport.
Dr. Urth chuckled. 'How nice if we could test this matter. If there were only some physical manner in which we could differentiate