a discoloration in the ground; tests show the black rock is draining silicon from everything it touches. Dr. Reynolds says research indicates that one possible function of silicon in the human body is to maintain tissue flexibility. They realize that absorption of silicon is the cause of Ben's death and Ginny's condition. Steve prepares and administers a silicon solution injection to Ginny. Dave and Arthur trace the fragments to the crashed meteor. Arthur deduces that the meteorite's atomic structure has been radically altered by the intense heat of atmospheric friction. Back in the lab, Dave and Arthur investigate why the black rocks seem to be multiplying. A piece of black rock falls into the sink and reacts when coffee is poured on it; the men then realize that water is the cause of its growth. With a rainstorm now in progress, they return to the desert and see the black fragments growing into stories-tall monoliths that collapse under their own weight, breaking into fragments, each fragment then repeating that cycle. Dave realizes that the monoliths' path will take them directly through San Angelo, and from there the monoliths could spread and possibly threaten all life on Earth. They explain the threat to Police Chief Dan Corey, who makes plans to evacuate San Angelo. The governor is notified, and declares a state of emergency in the San Angelo area. At the hospital, Ginny revives, and Dave deduces that something in the silicon solution will check the fragments' growth. More locals are rushed to Dr. Reynolds' office in various stages of petrification. With little time left, and the telephone and electricity cut off, the monoliths continue to multiply and advance, soaking up water from the rain-soaked soil. Through lab experimentation, Dave and Arthur discover the monoliths can be stopped with a simple saline solution, a part of Steve's silicon formula. Dave plans to dynamite the local dam and flood the nearby salt flats, creating a large supply of salt water. Because the dam is private property, Dan attempts to contact the governor for permission to blow up the dam. Knowing they must halt the monoliths at the canyon's edge, Dave acts without waiting for the governor's approval. A torrent of water flows over the salt deposits at the canyon's edge, reaching the monoliths; their growth is halted. Dan reports that he reached the governor who told him not to blow up the