The Wildfire team theorizes that Andromeda may have been intentionally sent as part of an alien invasion force. They discover that a specific, rare bacterium can destroy Andromeda and rush to manufacture enough to stop the outbreak. Meanwhile, the reporter flees both the spreading plague and government assassins, and rescues a young woman in the process.
Just before the outbreak can become uncontainable, the bacteria is dropped into the infected zone and kills Andromeda, but a military attempt to save a sample leads to an outbreak within the underground lab. The team must race to stop a nuclear countdown designed as a last defense against a lab breach – a blast that could feed Andromeda and reignite the outbreak.