Kathy Rodriguez is a geologist who has just lost her lover, John Hannebury, in an accident while investigating an unusual object discovered underground. Lina Thigpen is an experimental physicist who, with her colleagues at the Tesla Institute, helps to investigate the strange anomaly discovered by Rodriguez and Hannebury. It becomes apparent that, not only is it a time machine, but there are many more such machines - Timegates - in underground installations around the world. Both Lina and Kathy take part in the international time travel research program that is then implemented using the Timegates. But while commercial interests and the military constantly push to take over the program, both women are given opportunities beyond their dreams. Their stories culminate in a rescue mission that unlocks secrets that could change the world.