Dr Marissa Blumenthal (Nicollette Sheridan) has just been promoted to investigator at the world-famous Center for Disease Control. Her first case: an outbreak at a clinic in Los Angeles. It should be simple - but Marissa finds that this is no isolated outbreak. Soon, people are dying all over the USA. Moreover, the virus could have only one source: a high-security medical lab. Marissa moves closer to the truth, but each step she takes becomes more dangerous. Her home is vandalised, top-level medics are warning her off - and someone is trying to kill her...