Kyle rescues Dr. Sarah Jordan as Alan Farragut fights his own brother, Peter Farragut.
The uninfected are hiding in a secret bunker on the base as the CDC attempt to retrieve the canisters with the virus and the cure while the Ilaria assassins capture Hatake and force him to chose between which one of his children they will kill first.
The Navy prepare to implement Plan B, a final solution to ensure that the virus and everyone infected with it never make it off the island.
The Abbey becomes a house of horrors as Kyle struggles with his infection and Anne begins to shape a successor to Michael.
Alan, Kyle and Winger search the woods for the tree with red sap that might be a cure for the pathogen.
The Coast Guard arrives on the island to take the CDC team to another island to deal with another outbreak of the pathogen. Meanwhile, Sister Amy has to contend with Brother Michael and his plans.
As Peter gains a new cellmate, Michael takes extreme action when his followers begin to mutiny.
Peter and Jordan leave the safety of the Abbey to retrieve some specimens and discover just what’s living in the woods, meanwhile Sister Amy plots to make them leave forever.
Helix is an intense thriller about a team of scientists from the Centers for Disease Control who travel to a high-tech research facility in the Arctic to investigate a possible disease outbreak, only to find themselves pulled into a terrifying life-and-death struggle that holds the key to mankind's salvation...or total annihilation.