death, whose removal from the past would not have any effect upon the
casual chain of events affecting the present."

A warning buzzer rasped in Benson's brain. He nodded, poker-faced.

"I can see that," he agreed. "You wouldn't dare do anything to change
the past. That was always one of the favorite paradoxes in time-travel
fiction.... Well, I think I have the general picture. You have a
dictator who is tyrannizing you; you want to get rid of him; you can't
kill him yourselves. I'm opposed to dictators, myself; that--and the
Selective Service law, of course--was why I was a soldier. I have no
moral or psychological taboos against killing dictators, or anybody
else. Suppose I cooperate with you; what's in it for me?"

There was a long silence. Walter and Carl looked at one another
inquiringly; the others dithered helplessly. It was Carl who answered.

"Your return to your own time and place."

"And if I don't cooperate with you?"

"Guess when and where else we could send you," Walter said.

Benson dropped his cigarette and tramped it.

"Exactly the same time and place?" he asked.

"Well, the structure of space-time demands...." Paula began.

"The spatio-temporal displacement field is capable of identifying that