What if every drop of water turned deadly? The town of San Paulo, California is in the midst of one of its worst heat waves. To make matters worse, what appears to be an epidemic caused by food poisoning has spread among residents like wild fire. Water filtration engineer Bob Miller has a hunch that proves to be terrifyingly true - the city's water supply is contaminated. Hospitals are packed. The city is quarantined. And the heat wave keeps coming. With infections multiplying, and Bob's own son close to death, he races against time to stop the epidemic.