The battle against the Observers goes for a trip as  ‘Fringe’ season 5 debuts its ninth episode of the final season “Black Blotter,” where Walter drops acid and fights to avoid turning into his former, villainous self, while the team follows a mysterious radio signal to hopefully uncover information about the even more-mysterious Donald.

Last week’s ‘Fringe’ episode “The Human Kind” saw Olivia retrieving an electromagnet from an oracle-like woman (Jill Scott), while the team tried desperately to convince Peter to abandon his hunt for Windmark and return to his humanity by ditching the Observer tech, so how does “Black Blotter” keep the final season in motion?  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’ season 5 episode 9 “Black Blotter!”

Astrid awakens in the lab to a mysterious noise, finding that Donald’s mysterious radio has whirred to life and begun broadcasting an unusual signal.  Astrid alerts Peter and Olivia to the development, but find Walter of little help, having dropped “Black Blotter” acid.  While the group ruminates what the radio might be broadcasting, Walter sees visions of a green fairy, and his former lab assistant Dr. Carla Warren (Jenni Blong).

Walter explains that he dropped the acid in hopes of remembering the plan before his previous, more villainous persona returns, one which increasingly drives him to leave the lab on his own and uncover more secrets. While Walter continues to hallucinate images from his past, including that of a younger Nina Sharpe, Peter recruits Anil for a device that allows them to track the radio signal, even if they haven’t cracked its meaning.

Having found the source of the transmission in a nearby woods, Peter and Olivia investigate a forest, finding a crashed RV and a number of skeletons surrounding it, Observers, Loyalists and Resistance alike.  Peter sees that the signal is actually only part of a relay, while Olivia finds that the RV driver’s corpse is that of Sam Weiss, whom only Peter and Olivia remember from the alternate timeline.

Meanwhile, Walter’s hallucination of Carla Warren tempts him to give into his former self, and leads him to find an old journal of his hidden in the laboratory.  Both the green fairy and Nina Sharpe urge Walter to resist, and dispose of the journal, in which Walter has a number of his past inventions and calculations drawn out in detail.

Walter next finds himself all the way in a Manhattan taxi backseat, the words “black umbrella” floating about his head, as Carla urges him to take his inventions into the nearest Observer precinct.  Just as one of the Observers begins to reach into the cab, Walter realizes that he hallucinated the entire experience, and is in fact on a Massachusetts dock renting a boat with Peter, Olivia and Astrid.  While Walter sees Donald’s location off in the distance as the great Emerald City, a number of Loyalists show up to the dock. Peter and Olivia take them on in a gunfight, and the group prepares to head downriver.

Rowing ashore, the group find themselves outside a house appearing to be the source of the radio signal.  A man steps out threatening them with a shotgun, shortly followed by the mysterious Observer child.  The man denies being “Donald,” and keeps his weapon raised even as Olivia explains what they’re doing there.  The man’s wife reminds him they knew someone would come for the boy eventually, and the man agrees to relent if only the four know the password transmitted over the radio. With the group at a loss to know the password, Walter lapses into an animated, Monty Python-style daydream, traveling the landscape and fighting off a darker version of himself, before standing victorious with a black umbrella.  Back in reality, Walter gives “black umbrella” as the password, and the man lowers his gun.

Inside, the couple explains how “Donald” left the boy for them to watch over in the early days of the resistance, who hasn’t aged or spoken a single word.  The man reluctantly accepts that the boy “Michael” was meant for great things, and says his tearful goodbyes as Walter, Peter, Olivia and Astrid leave with the boy in tow.

While Olivia serves their new guest cocoa back at the lab, Walter stews in all his old memories of Carla, Reiden Lake and his wife Elizabeth.  Walter resolves to burn the book containing his old experiments, despite the hallucinations insistence he’ll again become the man he used to be.  Suddenly, Walter looks down to realize there was never any book at all, and sees the darker version of himself standing before him, while Carla says “you’ve been him longer than you’ve been you.”

With only 13 episodes to its final season, it may have been a questionable choice to utilize a "weird" episode like "Black Blotter, even if it feels like some of the classic 'Fringe' stand-outs we've come to remember.  At best, "Black Blotter" at least delivers on advancing the plot with the re-introduction of the Observer child, still leaving "Donald"s identity for another day.  Only four episodes remain, so hopefully we're done finding the various pieces of Walter's master plan, and can instead focus on the endgame.

Did you get your fill of freaky ‘Fringe’ drama?  What did you think about the season’s ninth episode? Join us next week for another all-new ‘Fringe’ episode recap of “Anomaly XB-6783746” on FOX!