Star Trek: The Next Generation #63: A Matter of Conscience

Part 1 of 3. The Enterprise encounters a destroyed Cardassian vessel bearing a lone survivor - a Romulan who claims to be fleeing his government to prevent it from controlling a new virus that can destroy dilithium crystals, a tactical advantage that could upset the balance of power. But Picard believes there is much more to this story than the Romulan is willing to reveal.