In this episode, the science team goes on the offensive when Resistance Forces apprehend an Observer and the powerful portal-creating device he had with him. Astrid solves a critical puzzle that may turn the advantage to the Resistance forces. Meanwhile, Peter makes a pivotal choice when he learns of the advanced technology each Observer has implanted.
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Peter determined that the only way to fight the Observers was to become one himself.
Observers are featured in this episode.
Graffiti on an overpass in 'The Bullet that Saved the World' reads "Manifest Destiny", foreshadowing the Observer's shipping manifest the Fringe team decodes in 'An Origin Story.'
Graffiti behind Anil's van in 'An Origin Story' says "Ask Alice", foreshadowing the theme and title of 'Through the Looking Glass and what Walter Found There'.
Peter's grief over losing Etta in "An Origin Story" drove him to put Observer tech in his head to make him their equal. (Image 1)