In Los Angeles, Ritter (Jon Gries) is a National Guardsman and father. Zach (Christopher Masterson) and Bodi (Jake Muxworthy) are college students. Heera Bhatti (Shabana Azmi) and her son (Ajay Naidu) run a local store. When terrorists contaminate the city's water supply, all of them must contend with the volatile situation. Not only do they face the threat of dehydration, but also the wrath of other desperate citizens. Each group responds differently in their fight for survival.