As the gang hatches an illicit scheme to get to the bottom of the deep-sea mystery, John B confronts Sarah while Pope jumps at the chance for revenge.

As the gang hatches an illicit scheme to get to the bottom of the deep-sea mystery, John B confronts Sarah while Pope jumps at the chance for revenge.

Something unnatural is happening in the swamps outside Marais, Louisiana. When a mysterious illness strikes the town, CDC investigator (and former Marais native) Abby Arcane is sent to investigate.