Laura finds a piece of aquamarine glass on the New Jersey beach. But it’s not sea glass, it’s a miniature time-machine that transports her back 30,000 years to an earth threatened by an approaching asteroid. Kentir, leader of the project to destroy the asteroid has also brought to the land he calls Issa, Hua Te, a Chinese mage; Chac, an Aztec priest; and Marica, a woman from the 23rd century in hope one of them will have knowledge that will help. The project headquarters is a lovely, airy white building at the edge of a northern sea, but with tropical vegetation. Laura and the other time-travelers, along with Kentir, his brother, Thuban, and a few of their friends race against time to find a solution