Still in the states, and still heading south, Steve Backshall's journey from pole to pole takes him to Texas, home to the largest congregation of predators ever seen on Deadly. Harness and ropes in hand, Steve lowers himself into the depths of one of the most inhospitable environments on earth in order to literally hang out with a mega swarm of Mexican free-tailed bats. Above ground Steve and his team are on the hunt for the secretive mountain lion - a big cat that to date has always managed to elude him. Whilst tracking down this hard to find feline he gets wrapped up in a surprise encounter with a deadly spider and searches for a serpent responsible for more bites to people than any other venomous snake in the United States.