Without warning, a Starfleet ship is overwhelmed by a mysterious, alien aggressor -- one who appears to possess an intimate knowledge of the vessel's tactical technology. Then a second Starfleet ship is attacked. And a third. <P> Twenty-eight-year-old Jean-Luc Picard, captain of the <I>U.S.S. Stargazer</I> -- a <I>Constellation</I>-class starship -- is ordered to help form a desperate line of defense against the aggressor. But it seems nothing can stop the aliens' headlong plunge into the heart of the Federation. <P> Or rather, nothing in <I>front</I> of them can. Trailing one of the alien attack formations is a tiny Starfleet shuttle with a half dozen crewmembers aboard. One of them is Picard's first officer and best friend, Gilaad Ben Zoma. <P> Another is Arlen McAteer, the ambitious admiral who has made it his business to relieve Picard of his command. <P> Can Ben Zoma and McAteer work together to unlock the secret of the alien assault? Or will their differences sabotage their effort -- and deprive the Federation of its last hope for survival?