After shifty FBI Agent Mitchel Loeb orchestrated David Robert Jones' otherworldly escape from a German prison and Olivia's alarming abduction, indications of a larger threat begin to emerge. Adding to the intense circumstances, one of Olivia's former adversaries is called in by Internal Affairs to conduct a formal review of the Fringe Division, and Olivia's sister, Rachel, pays a visit. The timing couldn't be more inopportune, as Olivia, Walter and Peter race against time to solve the wildly grotesque murder of an esteemed epidemiologist - which may link to Olivia's own abduction - before a catastrophic epidemic is unleashed.