Star Trek The Next Generation, book 37 : The Last Stand
Brad Ferguson1995

In the middle of a routine mapping mission, Captain Picard and the crew of the USS Enterprise-D encounter a culture just on the edge of developing warp drive technology. When they survey the planet, they are startled by the sudden approach of thousands of spacecraft from an aggressive alien race bent on destroying this emerging culture. Now Picard has only days to resolve a conflict that has been going on for millennia. If he fails, billions will die, yet if he succeeds, he will unleash a powerful new threat to the Federation.