“No.” The entity appearing as my mentor stopped rocking. “Zachary, do you remember how you used to solve a Rubick’s Cube? Six sides, kept in flux, each move affecting at least three other sides. In every moment of existence there are varying moments within the spectrum of free will. You can remain in the mainstream or venture out into the radical, but each decision will create a domino effect upon the next. To survive Vostok’s darkness, you must figure out how to curve the elements that have brought about your death into a pathway that leads to your survival. That is the means to revealing more light, more energy. You’ll need this light to access the portal.

“You’ve methodically exhausted six of the seven accessible dimensions of the energy spectrum, leaving only violet, the last wavelength. The ice tunnel will collapse behind you as you leave, sealing off further communication. If you perish this time around, I cannot save you.”

My heart pounded with adrenaline as I moved through the ice tunnel, my eyes darting from the pulsating indigo light ahead to the Geiger counter in my hand.

Just a quick look. One quick look and I’ll have enough information to theorize cause and effect. Then I’m up the rope and climbing out of the chasm, and we’re back in the sub and en route to the north basin. Up the ice sheet and I’m done. Done with Vostok, done with Antarctica and its insane cold. Then it’s home to Brandy and William.

Wary of the time, I started to jog, counting each ice-crunching stride to gauge the distance back to the rope.

Twenty-one… twenty-two… twenty-three…

The indigo hue deepened to violet, reminding me of my fateful descent into the Sargasso Sea three years earlier, a mission that had led to my second drowning—a near-death experience that had changed my path in life.

Would this present decision alter my path again?

Not likely, it seemed. The tunnel simply dead-ended in a slab of volcanic rock.

I switched the Geiger counter to the magnetometer, the needle going haywire.

A magnified asteroid impact crater, just as I thought. What a waste of time. You let Ben and his crazy stories get inside your head.

Without warning, the violet light disappeared, and the tunnel swallowed me in its all-consuming blackness. I fumbled with my night-vision goggles. My surroundings reappeared in a faint olive-green, but everything felt different—cold, dead—and a surge of claustrophobia unleashed a wave of anxiety that sent me sprinting back down the tunnel.

I made it to the rope and immediately started to climb. I was halfway up when the bear-dog revealed itself to be alive, raising its head and upper body off the ice, crying out in pain.

The animal’s hip was broken. Had I delayed my ascent it might have caught me in those sharp canine teeth.