Thrice Upon a Time

SOS FROM A FUTURE
THAT WILL NEVER BE

It's amazing enough when Murdoch Ross's brilliant grandfather invents a machine that can send messages to itself in the past or the future. But when signals begin to arrive without being sent, Murdoch realizes that every action he takes changes the future that would have been . . . and that the world he lives in has already been altered!

Then a new message arrives from the future: The world is doomed!

Praise for a Science Fiction Superstar:

"A dean of hard SF . . . entertaining, imaginative yarn . . . sign up for this ride!"
—Publishers Weekly

". . . on the cutting edge of technology . . . Hogan's talent carries the reader from peak to peak in the story."
—Booklist

". . . fascinating notions and nonstop plot twists in a taut, gripping narrative. . . ."
—Kirkus Reviews

"First-class. . . ."
—Chicago Sun-Times

". . . cutting edge scientific approach . . . truly fascinating and hugely enjoyable."
—Starlog

Cover art by Patrick Turner

Paperback

This is a work of fiction. All the characters and events portrayed in this book are fictional, and any resemblance to real people or incidents is purely coincidental.

First printing, November 2000

Distributed by Simon & Schuster
1230 Avenue of the Americas
New York, NY 10020

Printed in the United States of America

ISBN: 0-671-31948-5

A Baen Books Original
Baen Publishing Enterprises
P.O. Box 1403
Riverdale, NY 10471
http://www.baen.com

Typeset by Windhaven Press
Auburn, NH

Electronic version by WebWrights
http://www.webwrights.com

To all at Del Rey Books—the other half of the team who never get mentioned on the cover

BAEN BOOKS by JAMES P. HOGAN