Complete story — includes the ending
A group of shapeshifters are stealing human heads, and it is revealed they are looking for a specific one. Walter visits the woman ( Theresa Russell ) he experimented on with psychedelics to see what she might still remember about the shapeshifters from her visions; she volunteers to help. After being drugged, she sees the shapeshifters again. Meanwhile, Olivia remembers her meeting with William Bell ( Leonard Nimoy ). Bell explains what the shapeshifters are looking for, and states she is the only person able to stop "The Storm". Olivia meets Nina, who explains that "The Storm" is an event that Bell theorized; when two universes merge, only one will remain in existence. This is what the shapeshifters are trying to cause. Later, Olivia discovers Charlie is dead and that a shapeshifter has replaced him, and kills him. The shapeshifters find the head they are looking for, and attach it to its body.
Sources and content license
Source and revision history · Adapted from Wikipedia contributors, Fringe season 2. HTML formatting and reference markers removed. · Content license