First Strike is the first novel in the Invasion! novel series.
Long ago, even before the days of myth and legend, our worlds belonged to them. Now they want them back...
Captain Kirk is stunned when the Federation receives an urgent plea for help - from the Klingon Empire. A mysterious starship has invaded Klingon space and resisted all efforts to destroy it. Establishing contact with the stranger's ship, Kirk discovers that it is only the vanguard of a vast alien Fleet obsessed with conquering the Klingons, the Federation, the Romulans, and all who dwell in the space that was once their own.