Watch Fringe Season 2 Episode 4 - Momentum Deferred online

Fringe division investigates a series of robberies of human heads that are linked to shapeshifters. Olivia is given a memory-jogging concoction by Walter made of flatworms. Walter finds that the shapeshifters are made of mercury and that the shapeshifter they thought was dead is still alive. Walter and Peter visit the woman that Walter experimented on with LSD to see what she might still remember about the shapeshifters from her visions. She immediately remembers Walter and volunteers to help. Back in the lab, they give her a dose of LSD and she sees the shapeshifters again. Olivia has a sudden rush of memories regarding her meeting with William Bell. He draws a symbol and says that the shapeshifters are looking for someone with that symbol on his head. He also tells Olivia that she is the only person strong enough to be the gatekeeper between the dimensions, because “The Storm” is coming. After Olivia wakes from her memories, she visits Nina Sharp, who explains that “The Storm” is William Bell’s theory that when the two dimensions collide, only one will remain in existence. The shapeshifters are trying to cause this. As the woman that Walter experimented on says good-bye to Peter, she pauses momentarily, implying that she realizes Peter is from the other dimension. Elsewhere, Olivia discovers that Charlie is the missing shapeshifter and kills him. At the end, the shapeshifters find the head they were looking for and attach it to its body.