Plucked from near-certain court-martial by order of Time Guard Command, Nathan Golich is ordered to rejoin his time jumper crewmates aboard Cygnus. With two other jumpships, Cygnus forms a unit called 1st Jump Squadron. Their mission: engage large Coethi formations threatening the very heart of the Alliance, the Urth-Sol system itself.
Immediately after jumping to Urth-Sol, Cygnus engages the Coethi and is damaged in the process, though the Bugs are driven off. Now Time Guard Intelligence detects large-scale Bug swarms moving out of voidtime to directly engage Urth itself. Golich and Alicia Yang are assigned to the one remaining operable ship, Majoris, and jump into Urth space, but the Coethi have already turned one of the crew and the ship is destroyed by sabotage from inside. Only Golich and Yang escape in a pod that crash lands on the Moon. After harrowing encounters with Bugs now occupying Urth's satellite, Golich and Yang are assigned by Time Guard to a mission that will take them back in time three hundred million years, to stop the Coethi from disrupting Urth's evolution and prevent the Bugs from interfering with Man's first appearance.
With Cygnus repaired and on-station, the time jumpers navigate an ancient time stream, straight into the face of a menace they never expected and never encountered before.
Tenth episode in the Time Jumpers serial.