Quarantine (Star Trek Voyager: Starfleet Academy #3)

Cadet Kathyrn Janeway is thrilled and nervous. She and four other cadets have just been assigned to the "U.S.S. Tsiolkovsky." It's their first real mission: to bring medical supplies to the planet Chatoob and help save a people condemned by air that hasn't been fit to breathe for centuries. But when Kathyrn analyzes the "poison" atmosphere, she finds no evidence of contamination. Is someone telling them lies? She's determined to discover the truth.
But when the curious cadets rush to help a sick old woman, they're trapped in a sealed room with people dying of the plague. Suddenly, they're cut off from their mothership, locked in a quarantine, scheduled to die -- unless Kathyrn can lead them out of the dead zone in time.