After shifty FBI Agent Mitchell 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.
Spoilers ahead. Coverage follows the scope labeled below.
Complete story — includes the ending
Olivia's former adversary, Sanford Harris ( Michael Gaston ), conducts a formal review of the Fringe Division. Olivia manages to free herself from her abductors. She, along with Walter and Peter, investigates the murder of an epidemiologist, who is killed by a man-made rhinovirus that creates a giant, slug-like single cell in his stomach. Olivia succeeds in connecting the murder to Loeb and obtains the necessary evidence to capture him. Olivia tries to question him about her abduction but he tells her that he was trying to save her. Olivia's sister Rachel ( Ari Graynor ) pays a visit with daughter Ella.