There's a killer on the loose in Galveston, targeting law enforcement officials and using a fatal injection of snake venom to take them down. Authorities have reason to believe the Veneno gang is behind the hits, and FBI Agents Leah Riesel and Jon Colbert team up to track down those responsible. Their best lead is an eyewitness who identifies a young man dumping the third body on a church doorstep. But their suspect has gone into hiding, and those closest to him are reluctant to reveal anything that might help investigators find him.