Lead Observer Captain Windmark (Michael Kopsa) brings in Phillip Broyles (Lance Reddick), warning him of a possible leak in the Loyalist forces, and then considers why Peter purchased the necklace from the shop.
The location of the necessary information is lost on a torn part of the tape, but Walter recognizes the story his past self was telling, pointing to a subway station deep inside Observer-controlled Manhattan.
Entering Manhattan through the Observer and Loyalist checkpoints would be impossible, but Walter directs them to a secret basement below his lab where he had stored elements from all the past Fringe cases.
Walter, Peter, Olivia, and Etta use a chemical developed by David Robert Jones that causes scar tissue to form over facial orifices (as seen in "Ability") which cause the guards at the checkpoint to suffocate, diverting attention long enough to recover the package from the subway tunnel.
As they review it, Broyles arrives, reunites with his former team, and explains how he was recruited into the Resistance after seeing and recognising Olivia in Etta and learning from her how to block his thoughts from the Observers.
"The Bullet That Saved the World" was written by co-executive producer Alison Schapker, and directed by House veteran David Straiton.
He summarized the show by saying, "Fringe was in rare form with a shocking turn of events that injected much-needed excitement back into the final season.
"[5] Cory Barker of TV.com named it the 20th best episode of the series, saying, "Etta's death was both gut-wrenching in the moment and important for the season's larger narrative interests.