Star Trek The Next Generation, book 20 : Spartacus
T.L. Mancour1992

Answering a distress call, the USS Enterprise-D finds a damaged Velman vessel called the Freedom. Jared, their captain, asks for assistance in repairing his ship, assistance Captain Picard and the Enterprise are only too happy to provide. Their relief efforts are interrupted by the arrival of an entire fleet from Vemla who claim that Jared and his crew are escaped slaves.

As Jared and his people plea for protection and the right to be free, Captain Picard is caught between the demands of his conscience and the dictates of the Prime Directive. And when the Vemlan fleet threatens to fight if the Enterprise doesn't stand aside, Picard must choose between the safety of his ship... and the annihilation of an entire race.