Up The Line
Author: Robert Silverberg
 
Time travel spelled problems for the couriers of the Time Service. Shuttling backwards and forwards over centuries they had to be wary of creating paradoxes - like meeting themselves watching the sack of Rome, or sleeping with their own ancestors. 
Of course, it also gave them the chance to amass wealth by the discreet use of their prior knowledge. The penalties were fierce and the Time Police implacable in their pursuit of lawbreakers. But it was still worth taking the risk.
Jud Elliot took it when he met the marvellous transtemporal paradox called Pulcheria. He couldn't resist her charms - the effects spanned generations, and set the Time Police on his trail.
 
SPHERE BOOKS 1st PUBLICATION 1975
ISBN: 0722178352