Fifth-grader Yin is really excited about her class trip to the International Space Station Three and the station museum's newest exhibit, the Star Cabbage, an alien plant discovered floating in space and considered harmless; but the station is on lockdown, the crew is not in evidence, and something large and growling is stalking the halls--but Yin is determined to investigate and find out whether the plant has mutated, or whether the real culprit is an organization, Earth First, that is determined to shut down all space research.