Black Fire

When sabotage strikes the "EnterpriseTM, Spock's investigation leads him into an alliance with the Romulan and Klingon empires against the Tomarii, a bloodthirsty race for whom war is life itself. Spock is declared a traitor and sentenced to the Federation's highest-security prison, and Kirk must choose between friendship and duty, with dire consequences for himself, Spock, and the entire Federation if he's wrong.