['Fringe' – 'Lysergic Acid Diethylamide']

Just when you thought 'Fringe' couldn't get any weirder, the show returned with one of its trippiest episodes ever.

This week's installment – with its wonderfully bizarre cartoon world, brain-melting sci-fi chicanery and drug-induced whimsy – will not soon be forgotten. It's the kind of episode that, years from now, will inspire us to say things like, "Hey, remember that crazy one they did in the third season? That was so awesome!"

But there's another reason this episode will remain stuck in our brains (or what's left of them) for years to come: It marked a major turning point for the show's heroine and resident whipping girl, Olivia Dunham.

Olivia has been put through the ringer more times than I can count over the past three years. She's been shot, drugged, manipulated and used as a guinea pig for about a dozen dangerous science experiments. Crazy scientists have even attempted to wipe her mind and replace it with a completely different personality. But Olivia has always come out the other end of these trials unbroken (for the most part). And, sometimes, these challenges inspire her to take another step closer to fulfilling her full potential.

After the insane events of this episode, it looks like Olivia is finally ready to become Super Olivia! Forced to examine herself inside and out, she discovered that she was consumed by paralyzing fear. In the end, she conquered her fear and accepted what Walter and Belly knew all along -- she's special, and she might even be strong enough to save the world(s).

She's not afraid to move forward anymore, and judging by that final scene, it seems that Olivia's head-trip will probably inspire her to make some big changes in her life. But perhaps it's too early to speculate on what exactly those changes will be and how they'll affect the show. For now, let's explore the mad, ambitious spirit and the geeky and fearless joys of this episode starting with ... two thousand milligrams of LSD, on the double, Astro!

This was an incredibly emotional episode, but it was also one of the funniest and goofiest hours of 'Fringe' we've seen all season. Inside of Olivia's subconscious, we witnessed cartoon zombie attacks (a fun parody of 'The Walking Dead' featuring what looked like an army of undead Brandons), Walter crotch grabbing, and cartoon William Bell riding a hog. Strange, ambitious stuff!

The comedy kept going back at the lab with hilarious scenes of Broyles tripping his brains out. It was a treat to see Broyles drop his sharp intimidation act and de-evolve into a Deadhead, comparing red licorice to Bernini's spirals at St. Peter's basilica.

But Broyles' trip wasn't all smiley faces and cartoon birdies; he went to a dark place and admitted, "I saw death, all of it. And it was me," referring to the image of his dead doppelganger from The Other Side. Luckily, Astrid is a born guide who was there to hold his hand through the long, strange trip.

The writers (Jeff Pinkner, J.H. Wyman, and Akiva Goldsman) were clearly having fun with the whole 'Wizard of Oz'-meets-'Inception'-meets-'A Scanner Darkly' vibe and presentation here, but 'Lysergic Acid Diethylamide' was firmly rooted in character and emotion, and it hit a few emotional beats that we'll surely see resonate again before the season ends.

Walter was clearly still troubled by the thought of the doomsday machine and Peter's role in what could turn out to be the end of the world(s). Belly's words to Walter in the airship reminded our favorite cuddly mad scientists to trust himself. "Now you possess the wisdom of humility," Belly told Walter. "The decisions you make will be the right ones. The direction you chose to take will be just." It was a poignant moment between two old friends, and the scene -- along with Bell's insistence that he knew the "dog wouldn't hunt" -- erased any doubts I had about William Bell's moral integrity here. Turns out the guy was on our side after all.

And it also turns out that Peter truly does deserve Olivia's love. His deep feelings for her and his knowledge of her heart led him straight to her secret, safe hiding place – no, not the house with the red door, but inside the little girl on the day before the Cortexiphan trials began.

Thanks in part to Peter's love and persistence, Olivia found the strength to trust herself and to fight against the fears that overwhelmed her. (Thankfully, the show spared us the visual of cartoon Olivia going all Buffy on her dream demons, which might have been a little much.)

So why did everything become animated about 18 minutes in? Probably because it was a cool and interesting thing to do. Or, perhaps, because Leonard Nimoy was unable to physically show up to play William Bell and could only record his voice for the part (he has retired from acting, after all). Whatever the reason, it mostly worked, despite the animation looking a little stilted and video game-y at times. It'll be fun to see 'Fringe' try to top this one next season.

I'm sure some will argue that 'Lysergic Acid Diethylamide' was simply a fun but frivolous detour from the overarching War of the Unverses plot, but I disagree. Olivia, Peter and Walter all learned new and important things about themselves here -- things that will matter once the war really starts to heat up.

Finally, what are we to make of the 'Zeppelin Man' who was running around inside of Olivia's mind? Belly assumed that he was some figure from her past, but Olivia claimed she'd never met him before. Was Olivia right when she said, "I think he's the man who's gonna kill me" before casually taking a bite out of a piece of toast?

And with that perplexing but intriguing ending we move forward, unafraid and ready for more.

Other thoughts:

- Watching Walter mourn Belly broke my heart. Even 'Zoom' couldn't cheer him up.

- Olivia's childhood home had a red door. Makes you wonder if there's any connection to the Other (red) universe there.

- "Aye Aye Captain!" They had to add a 'Star Trek' nod for what looks to be Nimoy's final episode.

- No, I don't think Broyles is an Observer!

- Friday was Anna Torv's birthday. Celebrate by watching this episode again!

'Fringe' airs Friday nights at 9PM ET on Fox

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