IT IS NOT EASY TO DISTINGUISH THE GOOD GUYS FROM THE BAD GUYS. THEY DRESS ALIKE, AND THE WEAPONS ARE CONCEALED. THE ONLY DIFFERENCE IS INTENT, AND YOU CAN’T READ MINDS.

STAY IN THE DARK LONG ENOUGH AND YOU MAY HEAR AN OCCASIONAL DISTANT SHRIEK OR BLUNDER ACROSS A BODY.

HOW DO YOU SURVIVE THE NIGHT? THE LAST THING YOU WANT TO DO IS SHOUT, “I’M HERE!” THE NEXT TO LAST THING YOU WANT TO DO IS TO REPLY TO SOMEONE WHO SHOUTS, “I’M A FRIEND!”

WHAT YOU WOULD LIKE TO DO IS FIND A POLICEMAN, OR GET OUT OF THE PARK. BUT YOU DON’T WANT TO MAKE NOISE OR MOVE TOWARD A LIGHT WHERE YOU MIGHT BE SPOTTED, AND IT IS DIFFICULT TO FIND EITHER A POLICEMAN OR YOUR WAY OUT WITHOUT MAKING YOURSELF KNOWN. YOUR SAFEST OPTION IS TO HUNKER DOWN AND WAIT FOR DAYLIGHT, THEN SAFELY WALK OUT.

THERE ARE, OF COURSE, A FEW OBVIOUS DIFFERENCES BETWEEN CENTRAL PARK AND THE UNIVERSE:

THERE IS NO POLICEMAN.

THERE IS NO WAY OUT.

AND THE NIGHT NEVER ENDS.

EXCERPTS END

“Anything else?” Isak asked, surveying the grim faces seated around his balcony table. The small gathering included Sargenti; Bishop, who had just been promoted to the rank of general; a second general named Stoff; and Azim Babu, the director of Ceres’ rapidly expanding astronomical observatory.

“Yes,” said Sargenti, “there’s that mystery call from Earth. It keeps coming up at us, louder every day. It’s always the same—latitude and longitude and pleas to come at once. They’re starving down there, so they say. And then there’s this …”

Sargenti wiped the SETI excerpts from everyone’s pad and replaced them with maps of the sky showing patterns of gamma ray bursts, each burst indicating an engine burn, presumably a course correction. The images reminded Isak of a bad microscope displaying unknown organisms, but it was all too clear what was happening.

At least six antimatter-driven rockets were moving between the planets. One of the ships seemed actually to have reversed course and was headed directly for Earth. Isak longed to believe there were people in them, but he knew better. Graff, Nautile,

Melville, and every other starship he knew to be of human origin was gone. He knew more—much of it from the new telescope array.

The Saudis, returning from Tau Ceti with their antimatter tanks nearly empty and finding the Mercury Power Project obliterated, had begun moving toward the imagined safety of the Asteroid Belt, their engine bums pointing like glowing fingers toward the halfdozen islands of civilization they suspected might still exist.

“My God!” Isak had exclaimed. “Why don’t they just paint a big red X on us!”

The Saudis had no idea of what had happened to the solar system; and the asteroid survivors, forced into stealth, refused to answer their queries. Unaware that something might be hunting them, the starships, like the mystery caller on Earth, had broadcast loudly on all wavelengths, demanding information and assistance. In the end, some of the colonies had brought magnetic rail guns to bear on their own spacecraft—which they knew were cruising with low antihydrogen reserves, at interplanetary speeds of only 325 kilometers per second, 28 million kilometers per day—and they fired hastily fabricated smart bombs equipped with maneuvering thrusters, gamma detectors, and mini radio telescopes. When the last of the Valkyries exploded into searing hellfire, it was impossible to verify whether the aliens or surviving humanity had gotten to them.