Bob is put into a medically-induced coma to reduce the risk of infection resulting from the brain surgery he received at the end of last season. David and Carlos investigate a drug-resistant strain of TB that is killing Mexico's Zapatista Revolutionaries. Rachel and Mayko travel to a farming community where citizens are suffering a rash of horrific injuries due to an inability to feel pain.

As if being HIV positive wasn't enough, Wes is accidentally scratched by a needle tainted with a genetically-engineered, virulent strain of Hepatitis C.