It also made him nervous.

Under intense pressure from enemy warships in the Epsilon Eridani system – the location of the UNSC’s last major naval base, Reach – Cortana had been forced to launch the ship toward a random set of coordinates, a standard procedure to lead the Covenant forces away from Earth.

Now it appeared that the men and women aboard the Pillar of Autumn had succeeded in leaving their original pursuers behind, only to encounter even more Covenant forceshere... wherever “here” was.

Cortana aimed a long-range camera array at the ring and a close-up snapped into focus. Keyes let out a long, slow whistle. The construct’s inner surface was a mosaic of greens, blues, and browns – trackless desert, jungles, glaciers, and oceans. Streaks of white clouds cast deep shadows on the terrain below. The ring rotated and brought a new feature into view: a tremendous hurricane forming over a large body of water.

Equations again scrolled across the AI’s semitransparent body as she continued to evaluate the incoming data. “Captain,” Cortana said, “the object is clearly artificial. There’s a gravity field that controls the ring’s spin and keeps the atmosphere inside. I can’t say with one hundred percent certainty, but it appears that the ring has an oxygen-nitrogen atmosphere, and Earth-normal gravity.”

Keyes raised an eyebrow. “If it’s artificial, who the hell built it, and what in God’s name is it?”

Cortana processed the question for a full three seconds. “I don’t know, sir.”

Regulations be damned, Keyes thought. He took out his pipe, used an old-fashioned match to light it, and produced a puff of fragrant smoke. The ring world shimmered on the status monitors. “Then we’d better find out.”