Endless Summer froze for a full second as it processed this. "There is no such launch facility on this planet. Funding for such—"

"I wrote the subroutines that you are now accessing to generate that falsehood," Dr.

Halsey said. "I do recognize my own handiwork."

She gathered Cortana's log, the files on the Cote d'Azure rock, and the scant data collected on the ruins and crystal found under Castle Base on Reach—copied them to the AI's file transfer directory.

Endless Summer cooled to fluttering green light. "I see," he whispered. "The Forerunner technology… Halo… such an amazing destructive force. This verifies many outstanding hypotheses."

"Then you agree we need to get a message to UNSC FLEET-COM. We need to control this technology, or failing that, destroy it."

He set aside his spear and held up both hands. "I… delayed using the COM probe. I had hoped we could survive until scheduled reinforcements arrive in three weeks."

Dr. Halsey sensed a microsecond hesitation in his words.

"That is not the entire truth," she said. "What are you omitting?"

He crossed his arms. "Colonel Ackerson is wise to fear you. Very well, Doctor, the COM probe launches from an underground gauss accelerator. A Shaw-Fujikawa translight generator then focuses the Slipspace rent in high orbit to avoid the obvious ramifications of an in-atmosphere transition."

"The probe launch and transition," she said, "would be like sending up a signal flare."

Endless Summer faded to a black-and-white ghost.

"The Sentinels will find the launch facility," he said, "and perhaps the passages that lead to the heart of the Zone 67 base, and me."

"Override self-perversion imperative," Dr. Halsey whispered. "Command FOXINTHEHENHOUSE /427-KNB."

"There is no need. Doctor," Endless Summer said, and held up his hand. "I understand my duty all too well. If they find me, there are explosive charges in place. I am prepared to die a good death. Are you?"

They starred at each other for a moment. Dr. Halsey wondered if this courage was a trick, a programmed facade… or real self-sacrifice.

"I'll prepare the message," she said. "I know precisely who at FLEETCOM to send it to.

They'll listen to me."

"Of course," Endless Summer said with a careless wave. "I find such low-level human communications distasteful."

"One more thing," she said. "Here are my personal conclusions linking the collected Forerunner data. You deserve to know everything."

She dropped her notes into his FTP directory—along with a capture worm in the footer of the data. It would copy and transmit every file Endless Summer accessed with her notes open.

Multiple files immediately began to flash-transfer to her laptop.

"Thank you," he said and his eyebrows quirked up. "Your logic is impeccable."

"Allow me a moment to draft the note," she said.

Endless Summer bowed. "I shall prepare the COM probe." His hologram faded.

Dr. Halsey decrypted the stolen files, and alien hieroglyphs streamed on-screen.

"What are those?" Mendez whispered, leaning closer.

"Forerunner language samples from these ruins, I surmise," she said. "Along with theoretical translation variants."

She searched for pattern matches in Cortana's log, and then cross-referenced the stellar coordinates embedded in the Cote d'Azure rock. There was a match: the symbol for the Halo construct.

She double-checked the stone and found coordinates for Onyx and a matching symbol in Endless Summer's database.

"What does that mean?" Mendez asked, pointing to a double-lobed icon.

"This," she whispered, "roughly translated, it means 'shield world.'"

"Funny thing to call a place," he observed.

In a moment of clarity she understood—not everything but enough to see a glimmer of the Forerunners' plan.

For every coordinated military effort there were offensive and defense aspects: attack, reinforcement, and, if needed, retreat. The Halo construct was only part of the Forerunner plan. Whatever was happening on this world was another portion of their strategy—triggered when Halo had been activated.

Onyx, the "shield," it was something Dr. Halsey might be able to use for her own purposes.

She rapid-fire typed a message to Lord Hood at FLEETCOM, requesting a large military force to be sent, explaining that the Forerunner technology here might turn the tide of the war. She then encoded Cortana's logs and the other data… in case Admiral Whitcomb and the other SPARTANTIs never made it back to Earth.

The hologram pad warmed and Endless Summer reappeared.

"COM probe launcher prepared and Slipspace generator capacitors charged," he said.

"You have the message. Doctor?"

She sent him the files.

"Concise and devoid of elegance," Endless Summer remarked. "What I have come to expect from human communication."

"Upload and send it," Dr. Flalsey told him.

"Accelerator primed, Slipstream transition matrix formed." His image dimmed. "COM probe away."

Endless Summer then frowned, and a ripple of static passed though his image.

"There's an anomaly," he said. "I'm keeping the Slipspace matrix open and running probe diagnostic."

"Explain," Dr. Halsey demanded.

"I am receiving a UNSC E-Band signal, bounced from the probe back to us, a transmission originating inside Slipstream space." He furrowed his brows. "This should not be possible. The energy required would be more than the output of all UNSC assets combined."

"It's not possible with our technology," Dr. Halsey said. "Download that message—put it on speaker while the probe is still in range."

A woman's voice filled the bunker. It was static-filled and choppy.

And unmistakably Cortana's.

"This is an automated message from UNSC MIL AI SERIAL NUMBER: CTN 0452-9.

"All UNSC personnel heed and stand to.

"I am declaring general emergency codes Bandersnatch and Hydra."

"Bandersnatch" was the code for radiological- or energy-based disaster. Dr. Halsey had heard this used before from planetary bombardment by Covenant plasma and during the UNSC nuking of the Far Isle Colony to put down the rebellion of 2492.

"Hydra," however, she had never heard used before. It was reserved for imminent threat from biological weapons of mass destruction.

"In Amber Clad has successfully followed the Covenant ship from New Mombassa to its destination, another Halo construct (stellar coordinates embedded).

"We discovered there are more Halos distributed throughout the galaxy.

"Covenant base ship and fleet are here en masse guarding Delta Halo.

"Parasitic infestation known as the Flood has contaminated this construct.

"Flood attempting to escape. Strategies suggest a hitherto unknown coordinating intelligence.

"Highest possible threat assessment from biological contamination and radiological annihilation from Halo detonation.

"Suggest FLEETCOM neutralize the Covenant-controlled Forerunner command vessel.

Be advised SPARTAN-11 7 onboard.

"Additional: Suggest FLEETCOM Nova-bomb the Delta Halo system to counter the imminent biological threat.

"Message ends."

Cortana had to be using the Forerunner technology to send this message through Slipstream space. But would any UNSC ship hear it? They weren't designed to detect signals in the notoriously unpredictable transdimension.

"COM probe almost out of our range," Endless Summer said. "Slipstream space matrix collapse imminent."

Dr. Halsey rapidly typed on her laptop. "Link to the COM probe," she told Endless Summer, "and amend our message with this. Calculate a frequency shift to match Cortana's signal, and resend our message from the probe inside Slipspace."

"Linked with probe." Endless Summer stared into space. "Stand by."

If this worked, Cortana's signal would act as a transluminal carrier wave. If the Slipstream space monitoring station on Earth had its ears open, their message would get to FLEETCOM in minutes instead of weeks. Possibly in time to do some good.

"Done," Endless Summer announced, "but verification impossible. Slipstream matrix has collapsed."

Dr. Halsey sighed, hoping the amended message had gotten through, and hoping she had done the right thing.

So much depended on her lies.

She glanced at the additional message she had typed.

"HOOD, YOU'LL HAVE YOUR HANDS FULL. REVISE REQUEST: SEND ELITE STRIKE TEAM TO RECOVER TECHNOLOGICAL ASSETS FROM ONYX. SEND SPARTANS."

CHAPTER TWENTY-TWO

1440 HOURS, NOVEMBER 3, 2552 (MILITARY CALENDARS \ SLIPSTREAM SPACE- UNKNOWN VECTOR\ ABOARD UNSC PROWLER DUSK

Commander Richard Lash hovered over Lieutenant Yang's shoulder, watching the screen for a blip—waiting for a single titanium ion to be sniffed by the sensor array on the Dusk's nose.

Lieutenant Yang shifted in his chair. "Sir, it's been fifteen minutes. I'm going to purge the collectors and recalibrate."

"Wait," Lash said.

"Yes, sir." Yang smoothed over his eyebrow, a nervous habit.

Five minutes ticked off on the clock as Yang and Commander Lash waited.

"Accurate timekeeping" was an oxymoron in Slipstream space. Still, Lash held on to some illusion that he was in control and not flying blind, chasing a trail so faint it might qualify as nonexistent after a Covenant capital ship and the UNSC destroyer In Amber Clad.

A single spark lit the screen.

"Got one," Lieutenant Yang cried. "Mass spectrometer pegs it as titanium-50. Consistent with UNSC battle plate. One of ours, sir."

"Very good." Commander Lash clapped his hand on Yang's shoulder. "Keep watching."

He pushed off and drifted back to the captain's chair.

Lash felt uneasy sitting here; it really belonged to Captain [glesias, but he was in rehab back on Earth. Radiation treatment for six months. This war would probably be over by then.

He sat and clicked the harness on. For better or worse he was in charge now.

Probably for the worse, because this mission was a cross between a wild-goose chase and pure suicide.

His prowler, Dusk, had been close enough to act when In Amber Clad had entered the Covenant capital ship Slipspace rift as it left New Mombassa. They were one of four UNSC ships with charged Slipspace capacitors, and nimble enough to make the transition before the overpressure wave generated by an in-atmosphere transition crushed them.

Miranda Keyes was the ballsiest officer in the fleet to go after that Covenant ship on her own. Was she nuts? Or trying to live up to the legendary reputation of her father?

Lash would never know what that felt like. His dad had been a welder on the Cradle … at least before the Cradle had been destroyed at Sigma Octanus earlier this year. Dad had always wanted to be a hero. He'd gotten his wish.

The Dusk—with the two frigates Redoubtable and Paris, and the corvette Coral Sea— had approximated the entrance vector of the Covenant ship, hoping to find out where they were headed, that or assist In Amber Clad in blowing her to hell.

They had been caught in the wake of the Covenant craft and accelerated to many times the maximum velocity of any UNSC ship in Slipspace. A lucky break. They'd have never caught it otherwise.

Technically "acceleration" and "velocity" were the wrong terms. They didn't map to the eleven nondimensions of Slipspace, but Commander Lash had never gotten the knack of thinking so abstractly. He left that to his NAV Officer.

What this wake effect meant in concrete terms was Covenant ships traveled geometrically faster from point to point than their ships. One more strategic advantage the aliens possessed.

Commander Lash surveyed his bridge crew. His first. Lieutenant Commander Julian Waters, sat next to him, scanning engine output semantics, his forehead furrowed with worry lines. At NAV sat Lieutenant Bethany Durruno running diagnostics, nodding off. She had ice in her veins, and sadly that calm-under-disaster fortitude was wasted in Slipspace. At the sensor station was Lieutenant Joe Yang; his youngest officer had seen more battle in the last four years than most saw in a lifetime, and he had suffered for it. Back in Engineering was Lieutenant Commander Xaing Cho, doing his job and the job of three other technicians.

They had all pulled double shifts, and the waiting was started to wear at them all.

The Dusk had been caught between rotations when the Covenant hit Earth. The ship normally had a crew of ninety They had to make do with a complement of forty-three.

And they were alone now, too.

The Redoubtable, the Paris, and the Coral Sea, with their larger engines, had moved ahead in the Slipstream wake. They'd passed out of limited COM range an hour ago.

"Sensor hits correlated, sir," Yang said.

A graph appeared on Commander Lash's display, plotting frequency and temporal distributions of their ion trail. It was a power-law decay.

That was the last ion they could expect. The trail was as cold as liquid helium. That meant either the Dusk had lost In Amber Clad … or it had dropped out of Slipspace.

"Stand by for transition," Lash said.

His officers snapped to, readying the Dusk to drop into the normal interstellar vacuum— or into the middle of a star or planet, for all they knew. There had been no time to plot a course.

Commander Lash took a deep breath. "Jettison the HORNET mines," he told Lieutenant Commander Waters.

"Sir?" he asked.

"Do it. Pull denotation codes and send then down."

Waters sighed explosively and nodded his head. "Yes, sir. Understood."

His junior bridge officers exchanged a look, but they all knew they had to lose the nukes.

They were going to remain stealthed, no matter what the cost, and fissile materials exiting Slipspace lit up with Cherenkov radiation—a signal flare to any Covenant ship within light-minutes.

"Mines away," Waters whispered.