Freefall by Brian Williams

Taking it down a whole 'nother level, Will and Chester journey to the center of the earth in FREEFALL. By the authors of the NEW YORK TIMES Bestseller TUNNELS and its sequel DEEPER!

DEEPER sent Will and Chester into FREEFALL-- tumbling through the subterranean Pore with the evil Rebecca twins in hot pursuit, both toting phials of the lethal Dominion virus. When, where, will they ever land?! Just when the drop seems infinite, the boys hit bottom, and find themselves in a realm of near-zero gravity atop a giant spongy fungus stuffed with artifacts from some lost golden age. But they are not alone. And above ground, black-clad Styx are sprouting like poison mushrooms, dead-set on spreading their plague!