The Time Snatcher by Randall Garrett - Tampering with events of the past could bring disastrous results in the future. It was why Brek was given a pair of six-guns to catch—The Time Snatcher.

"We're in a hell of a jam, Brek," the Councillor said. "If Sagginer isn't stopped, he'll change history. The situation's desperate."

Time Patrolman Brek Halliday nodded in agreement. It was a tense situation. Time travel, he knew, was possible only so long as the traveller into the past did nothing that would change history significantly; the time-stream itself would straighten out little changes in the past so that overall history would remain the same.

But a big change was something else again. If you stick your finger in a river, there are a few ripples around it, but the flow of the river remains the same. If you build a dam, though....

"When is he?" Brek asked. "Do we know?"

"Fortunately, yes. He forced one of our operators to use one of the chronokinetic projectors, and then kidnapped her and took her with him. But he didn't know that the power drain was measurable and had been recorded on the meters. We know how much energy he used, so we know how far into the past he went. We've got him pinpointed in the area of the old United States, somewhere between 1880 and 1895."

"Who was the girl he kidnapped?" Brek asked.

The Councillor smiled apologetically. "Dori Clayton."

The muscles of Halliday's jaw tightened. "I see," he said stiffly. "When do I leave?"

"We'll prepare you immediately. It's going to be a touchy job to get both of them out of there, so watch yourself."

"Don't worry," Halliday said quietly. "I'll manage it." He walked out, eyes hot with rage, thinking of Dori in Sagginer's clutches. His hands slowly clenched and unclenched as he headed down the long hall.