The battle against the Observers has a September revelation as ‘Fringe’ season 5 debuts its eleventh episode of the final season “The Boy Must Live,” the team tracks down a now-human September (Michael Cerveris), learning both the origins of the Observers and the details of Walter's plan before being forced to make a daring escape and sacrifice.

Last month’s ‘Fringe’ winter finale “Anomaly XB-6783746” saw Walter and the others attempting to communicate with the Observer boy Michael, while Nina Sharpe (Blaire Brown) made a deadly sacrifice and the identity of the mysterious “Donald” was revealed, so how does “The Boy Must Live” prepare us for next week's 2-hour series finale?  How will season 5 of ‘Fringe’ close out the epic saga?

Read on for your in-depth recap of everything you need to know about ‘Fringe’s ante-penultimate episode of the series “The Boy Must Live!”

Amber-cutting late one night in the Harvard lab, Peter finds himself startled by a similarly-sleepless Walter, who wants to continue their recent progress by utilizing LSD and a deprivation tank to unlock more of his memory with Donald/September. After stripping down and setting up, Walter explores the memory further, realizing himself to be in an apartment in Brooklyn, where Walter optimistically hopes they can still find September even 20 years later.

Elsewhere, Windmark ruminates on the recorded description of a child Observer, before being summoned to meet with his Observer superior, in a polluted, futuristic Manhattan 2609!

Arriving in Brooklyn, Peter questions what has his father so suddenly optimistic, to which Walter reveals that Michael’s touch restored his memory of Peter’s timeline and their previous life together. The two share a tender bonding moment, though wondering why Michael didn’t restore any memories of Walter’s plan.

The pair find their way to the apartment building from Walter’s vision, along with Olivia and Michael, and thankfully find a waiting September upstairs, very much alive and happy to see them. Inside the group swap stories, September explaining how the Observers removed his device and restored his humanity as punishment, before he adopted the name “Donald” after ‘Singing in the Rain’ star Donald O’Connor.

Turning to Michael's origins, September explains that a scientist from the year 2167 discovered how to re-write the human brain to sacrifice emotions for intelligence, a process that eventually created the “Observers” they’ve come to recognize. Increased intelligence eventually eliminated romantic love, creating new reproductive technologies that clone and mature individuals from genetic donors.

In particular, “Michael”s maturation was halted once he was seen as a genetic anomaly whose brain developed differently than others, and nearly discarded. As the “donor” that created Michael, September explains that Walter’s relationship with Peter inspired him to save his own “son” from harm, and stash him away in the past, as we’d previously seen.

Meanwhile in 2609, Windmark shares his findings of September and “Anomaly XB-6783746” with his Commander, and expresses an admittedly unnatural desire to bend time and eradicate the fugitives that vex him so. Unwilling to risk altering history and the occupation they’ve established in 2036, Windmark’s superior dismisses the fugitives as inconsequential, and denies his request to kill them.

September explains to the group that Michael’s unfathomable cognitive abilities and balanced emotional awareness could prove to the scientists of 2167 that they needn’t sacrifice emotions for intelligence, preventing the Observers from ever coming into existence in the first place. Therein lies the true intent of Walter’s plan, assembling all their various components to build a device to send Michael forward in time to the year 2167! In a moment alone, Olivia expresses hope to Peter that resetting time could bring Etta back to life, though Peter seems doubtful of the idea.

Windmark returns to 2036, and having activated September’s tracking device, infiltrates the apartment only to find it empty. With Peter, Olivia, Walter, Michael and September already on the move to recover September’s stored tech, Windmark and his associate search the apartment, the associate quizzically tapping his foot to the sounds of jazz coming over the radio. The pair notice an anti-matter bomb within the apartment, but manage to teleport outside prior to its detonation.

Alone with September in his storage unit, Walter realizes that September’s words from the night at Reiden Lake “the boy is important, he must live” weren’t referring to Peter as originally thought, but rather Michael. Walter also admits that Michael’s touch showed him how he’d have to sacrifice his life as part of the plan, something September reminds Walter he chose willingly. September reminds him of his “White Tulip” as comfort, handing him the envelope the drawing was originally mailed in, though Walter can’t remember what he’d done with the drawing itself.

Outside, September opts to split from the group for now, promising to see Michael again. It isn’t long before the remaining four find themselves surrounded by roadblocks at every turn, Windmark hoping to smoke them out. Proceeding on foot, Michael and Olivia stealthily make their way past the blockades to the monorail, followed shortly by Walter and Peter. As the groups look to reunite, loyalists close in on Olivia and Michael’s position, to which Michael steps off the train and gives himself up before Olivia can react.

The train departs as the three watch Michael being led away toward Windmark, who greets the boy with a menacing “hello.”

And so, the final hours of 'Fringe' have truly begun, answering series-long mysteries about the origins of the mysterious Observers and now Walter's ultimate plan for saving the planet. Given only 13 episodes in its final season, it isn't exactly surprising for 'The Boy Must Live" to feel so exposition-heavy, though we hardly mind considering how long fans have been waiting for said answers to Observer origins.

Regardless of the exposition, the brief scenes afforded John Noble's Walter Bishop rank as some of the most heartfelt in the series, both in his renewed love for Peter and timid revelation of his inevitable sacrifice. We still can't help but wish that 'Fringe's final season hadn't taken so long to get to tonight's explanations, but have every confidence and heart-heavy anticipation of next week's two-hour series finale.

Did you get your fill of freaky ‘Fringe’ drama?  What did you think about the big revelations of the season’s eleventh episode? Join us next week for the final all-new ‘Fringe’ episode recaps of two-hour series finale "Liberty" and "An Enemy of Fate!"