After years of pushing the boundaries of interstellar spaceflight, Commander Maya Davis is ecstatic when she is promoted to captain.
But her enthusiasm wanes when she discovers that her new assignment is a one-way mission.
After taking command of the space-time vessel Yesterday, Maya must travel back in time to discover how and why a piece of 23rd century technology appeared 200,000 years earlier.
It's an exciting opportunity--except for the one-way aspect. The best minds of her time say it's impossible to return to the present.
Trapped in the distant past, Maya must choose between a peace that could condemn humanity to perpetual slavery, or a fight for freedom that involves deception, rebellion, and mass murder.
Whatever she decides, her actions may very well erase an entire civilization from history.
In the decade since returning from the Gliese 581 system, Commander Maya Davis has risen through the ranks while pushing the boundaries of deep space exploration.
When Director Sommerfield finally manages to access the device she found in the ruins on the Penphins' home world, the Interstellar Expeditionary Force grants Maya command of the Yesterday, humankind's first space-time vessel.
The fulfillment of a lifelong dream leaves Maya overjoyed. But her elation is crushed when she learns her first command is a suicide mission from which she can never return.
Based on the astounding information revealed by the device, Maya backshifts Yesterday 200,000 years into the past to confront beings who wield the ability to control humans like pieces of technology.
Uncovering the truth behind this powerful exospecies' visit to Earth presents her with a no-win situation.
If she thwarts their agenda, the human race she knows might never come to exist. But if she does nothing, she may condemn mankind to a fate worse than extinction.