The Serrano connection - Elizabeth Moon

Esmay Suiza had surprised everyone by becoming the youngest and lowest-ranking member of Fleet ever to win a major battle. Finding herself the senior surviving officer in a mutiny against a treacherous captain, she'd had no choice - it was do or die. And she'd risen to the challenge, saving Heris Serrano and her crew in the process. But instead of congratulations, her actions lead to a court martial for treason . . .

Esmay's boldness continues to reap her as much trouble as reward, when a very public argument makes her an enemy at Fleet School. When her classmate is abducted by a fanatical sect, Esmay is suspected of collusion. She feels she can formulate a rescue plan - but will anyone in Fleet listen to her now?