The new CBS drama series "Zoo" shows how humans are being hunted and violently killed by animals. We are becoming the extinct species, and Jack Oz and his team of researchers have not even got remotely close to figuring out what is driving these animals to unite against the destruction of humans.

In Season 1 Episode 4, "Pack Mentality", the researchers travel to Mississippi to investigate the wolves' attack on the prison guards. We saw in the previous episode, titled "The Silence of the Cicadas", death row inmate Evan Lee Hartley (Marcus Hester) was rescued by a pack of wolves. Before this rescue mission, Evan was seen staring through the fence, in the eyes of a lone wolf that sat in the prison yard.

Although a mysterious connection was established between the duo, no one anticipated the wolf to bring his pack into the prison, attack the guards and rescue the inmate. The brilliant scene ended with the wolf and inmate sharing a nod of acknowledgement and appreciation before parting ways.

Zoologist Oz (James Wolk), his partner Abraham (Nonse Anozie), journalist Jamie (Kristen Connolly) and veterinary pathologist Mitch (Billy Burke), along with the French intelligence analyst Chloe (Nora Arnezeder), who is in charge of the group as of the last episode, are trying to analyse what caused these animals to attack the prison.

Will Jamie's theory that chemicals produced by Reiden Global have caused animals to communicate with each other and attack humans hold true? If so, how was the mysterious prisoner Evan Hartley able to make a pact with the animals or at least wolves?

In the promo of "Pack Mentality", the researchers figure out that the animals who carried out the attack in China, Europe and Africa, were all injected with the same thing. Did Evan administer this injection, or was he among the few men whose innocence animals believed in?

Find out at 9.00 pm (EST) on Tuesday, 21 July, when "Zoo" Season 1 episode 4 will air on CBS. You can also live stream "Pack Mentality" via CBS Live TV.