The battle against the Observers reaches the beginning of the end as ‘Fringe’ season 5 debuts its penultimate episode of the final season “Liberty,” as Olivia realizes she must first cross over to the other universe in order to rescue Michael from a base on Liberty Island, while Windmark realizes Broyles might be the traitor in his regime..

Last week’s ‘Fringe’ episode "The Boy Must Live” saw the team tracking 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, so how does “Liberty” kick off the 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 penultimate episode of the series “Liberty!”

At the Harvard lab, Peter, Walter, Olivia and Astrid try desperately to get a fix on where the Observers could have taken Michael, to no avail. Broyles doesn’t answer persistent calls from Olivia, but instead cons one of his Loyalist subordinates into giving up the boy’s location, despite the man’s worries about internal security and “The Dove.”

And where’s that boy, you ask? Why, held prisoner in a dismantled statue of Liberty! Windmark sits down with the boy trying to get any information out of him, but proves incapable of penetrating the boy’s mind. Instead, he ends up with a bleeding nose and eye, and tersely demands his subordinates scan the boy to find out what he is.

Broyles calls the team to inform them of his findings, though unfortunately Liberty Island has become a nearly impenetrable fortress from any angle. Olivia theorizes that crossing over to the parallel universe from their Statue of Liberty would enable her to enter with ease, thought Astrid reminds Olivia her Cortexiphan abilities were shorted out years ago. However, Walter agrees it might be possible to get them back.

Tapping into a spare store of Cortexiphan downstairs, Walter prepares Olivia for numerous drastic side effects from such an unorthodox dosing, but Peter objects to putting Olivia at risk. Wanting to honor Etta’s sacrifice and faced with no other option, Peter and Olivia agree to the procedure, provided they use Walter’s “window” to check the other side’s integrity first.

Windmark has his men scan the boy, still bleeding from the nose in his presence, while Walter, Peter, Olivia and Astrid set up the window in Battery Park. Thankfully, the other universe seems to be very much in tact, the bronze Statue of Liberty along with it. Meanwhile back at the Harvard Lab, Donald returns with his tech to find the facility empty, and begins working on the components for the machine.

The group visits a Resistance safehouse in order to begin the procedure, for which Olivia will need to be dosed in the brain-stem a nerve-wracking four times. After three doses, each more painful to Olivia than the last, Walter insists on administering a fourth shot of the drug, the pain of which causes Olivia to pass out.

Analyzing the results from scanning Michael, two Observer scientists deduce that his emotional and intellectual development far exceeds anything they’d previously thought possible. Meanwhile back at the safe-house, Walter comforts Peter about Olivia’s unconscious state, and nearly tells his son of his impending sacrifice before Olivia begins to wake. With little over three hours to cross over and back, Walter instructs Olivia to return immediately if she starts feeling any side effects.

The four travel to an alley that will lead to the alternate universe Fringe Division headquarters, and Peter and Olivia say their tender goodbyes in fear of the worst. Slowly, Olivia attempts to activate her ability, and finds herself firmly on the other side! Fringe Division detects the incursion, and send units to apprehend Olivia, alerting a visibly older Faux-Livia and Lincoln Lee (Seth Gabel) in the process!

After observing photos of Lincoln and Faux-Livia’s life together, Olivia explains to the pair that she was stuck in amber for 21 years, and brings them up to speed about her struggles on the other side. The Cortexiphan makes her a bit woozy, seeing visions of a young Etta, but ultimately Lincoln and Faux-Livia agree to take her to Liberty island. Back on our side, Donald continues working on the machine, only to find it quickly powers down once activated

Over in 2609, Windmark presents the boy’s scans to his superior, who believes it advantageous to continue studying the boy. However, given Windmark’s concerns about the boy’s relevance to the resistance, he agrees to study the boy after he’s been killed and dissected. Meanwhile at Liberty Island, Olivia and Lincoln express their lack of regret for the way their lives turned out, and Faux-Livia leads her to the proper room in the facility. Saying her goodbyes, Olivia crosses back into our side, only to find Michael absent. Instead, the Observer surgeons are preparing him to be dissected in another room!

Phasing in and out of either side, Olivia searches the facility for Michael, downing any Observers that cross her path. Finally, Olivia makes it into Michael’s room, and manages to cross back over before an Observer gets to her! The Observer manages to cross over with her, but Faux-Livia and Lincoln are waiting to take him down, as with any others that follow. Faux-Livia takes Olivia back to Battery Park, the pair say their goodbyes again, and Olivia makes one final cross back to our universe to find the team waiting for her.

The Loyalist guard from earlier is brought before Windmark, having been one of 3 people to know the boy’s location. He confesses that Agent Broyles convinced him to give up the details, and Windmark sighs in exhaustion. Elsewhere, Donald pays a visit to an unknown apartment, revealing his fellow Observer science team colleague December! End part 1!

Well, we were glad to be able to visit the alternate universe one last time, and gain a bit of closure on its characters, even if they didn't contribute much to the effort to rescue Michael. Beyond that, there isn't really much to say about the emotional content of the episode, so let's keep on rolling to part two!

Did you get your fill of freaky ‘Fringe’ drama?  What did you think about the penultimate episode? Stay tuned for the final all-new ‘Fringe’ episode recap of series finale part two, “An Enemy of Fate!”