In the twenty-second century, the people of Earth inhabit giant fusion-powered cities sprawling across the planet. What's more, they are hosting the Cephians, advanced plantlike aliens who have come to assess humankind's readiness to join their galactic community. Although they are friendly, the aliens have been in the solar system for forty years, and humanity's patience and trust are starting to wear thin-at times violently so.
Eminent astrobiologist Dr. Shana Savarino, however, admires the calm, quiet wisdom of the Cephians. She also has serious environmental concerns for the planet, as well as personal issues with humans, and so she prefers the company of the visitors. Meanwhile, when a team of human scientists discovers a powerful and mysterious object buried beneath the Chicxulub crater in Mexico-known as the dinosaur crater-it harbors a secret concerning humanity's origins. Accidentally awakened by nuclear explosions, the object now seeks to wipe out all life on the planet and in surrounding space, and it seems only Shana has a chance of stopping the disaster.
