Last night's episode of Fringe was far out, far around, and far down. The show returned to its acid-dropping roots, and everything was dreamy. But was it any good? We apply the acid test.

Spoilers below...

I'm going to come clean: I hate "going inside someone's head" episodes. I hate them for the same reason I hate holodeck episodes and "visiting the dream world" episodes. (Although I liked Inception, and I also liked the Buffy season four finale. So I'm not made of stone here.)

Generally, though, these sorts of episodes tend to offer really glib attempts at psychoanalysis, paired with "nothing is real" hijinks. (And they're often done on the cheap, especially when a show uses its regular sets to stand in for someone's subconscious mind.)

So how did "Lysergic Acid Diethylamide" compare to the "Sloan's unconscious mind looks like Deep Space Nine" episode and other similar gems? Pretty well, I guess... it gains points for its daring use of cartoons and other experimental motifs. (Although the cartoons were probably just necessitated by the fact that they couldn't get Leonard Nimoy back in the flesh.)

I guess the thing that's keeping me from whole-heartedly loving last night's episode is that the whole "William Bell takes over Olivia's brain" storyline felt unusually half-baked and boring, and an unnecessary detour from all the fascinating storylines the show has left up in the air. Now that it's over, I'm still not sure what that storyline accomplished, other than to throw out a couple new random plot threads.

So William Bell's whole plan was to take over Olivia's body temporarily, and then port his consciousness over to the body of a brain-dead patient. But this second procedure, with a portly bearded man covered with ice cubes, fails to work – and then Bellivia has a seizure and nearly dies. It turns out emergency measures are needed to keep Olivia's consciousness from getting lost, forever.

So "Belly", Walter and Peter drop acid and go inside Olivia's mind, where it turns out that Olivia is hiding from them, and her subconscious projections have turned hostile and are trying to kill her as well as the intruders. There were a few things I really liked about this whole scenario:

1) The way in which Peter has to save Olivia is by figuring out where in her imaginary world she would go to feel safe – so he has to save her by knowing more about her than anyone else.

2) There are random dream zombies.

3) They travel via dream zeppelin. Which is pretty cool, if you think about it. And the cartoon Walter falling out of the Zeppelin and waking up was a cool moment.

4) There's a really neat cliffhanger in the final commercial break, where both Peter and Walter have woken up, and it's up to Bell to save Olivia – but we're still not sure if Bell wants to save her, or himself. He has a perfect opportunity to dispose of her forever, and ensure that he gets to keep her nubile body for himself, and for a moment we're left wondering if that's what he'd planned all along.

Things I didn't really like that much about it:

1) The conversation between Walter and Bell felt like one we'd had a few times before. I really didn't feel like there was any unfinished business between Walter and William at all, and if William wasn't going to bust out with a brilliant solution to keeping "our" universe from unraveling, or some other actual sciencey stuff, then platitudes about age bringing wisdom, etc., felt pretty useless. Nobody loves you for your grandfatherly wisdom, Belly — they love you for your mad science skills! (Unless that scene was meant to be setting Walter up for a new round of hubris, in which he believes he's wise enough to make the right choice, but he's actually not. In which case, forget I said anything.)

2) I really didn't get the explanation of how Olivia was supposed to be safe in her own mind, but she took the opportunity of having Nimoy's katra in her brain to let her fears overwhelm her because she's her own worst enemy.

2) Olivia overcoming her fears and having some kind of catharsis. I just didn't buy it for some reason. Maybe because it was animated Olivia instead of Anna Torv, with her expressive face. Maybe because it felt too neat. Maybe because the little girl Olivia overcoming her demons felt way too much like my least favorite Buffy episode. Mostly, it felt too pat.

Oh, and I guess we'll never get to see Olivia deal with the revelation that Peter was the serial killer who led her on a wild goose chase for a whole episode, and he was lying to her for weeks about it. I have a feeling that's been swept under the rug, except for the dangling plotline of those shapeshifters' data disks. It's too bad, because I'd rather have seen Peter and Olivia deal with the fallout from his deceitfulness than see Anna Torv trying to do a Leonard Nimoy impression for an episode and a half, honestly.

When the dust all settles, Bell is gone, probably for good this time – and it's probably just as well, given that the show seems to have run out of ideas for him. Olivia seems happier and more confident, because she's faced her demons and stuff.

And then Olivia calmly drops the bombshell that retroactively makes the whole rest of the episode way more fascinating: The mysterious dude who was locked in the engine room of the cartoon zeppelin is someone she's never met before, but she's pretty sure he's going to kill her. Wha?

Meanwhile, in the episode's "B" plot, Broyles accidentally gets dosed with acid, which provides an opportunity for Lance Reddick to break out of his usual stoic mask and get downright silly, including contemplating the infinite expanse of a Twizzler. And for a brief moment, we also get to see Broyles process the trauma of meeting his own dead body from another universe.

I was sad, though, because I thought Astrid would finally get to be proactive and heroic in her own right, coping with stuff in the "real" world while the Bishops were inside Olivia's head. But instead, Astrid's role mostly consists of bringing people food and doing errands, as usual. At least she finally gets her own back when Walter calls her "Astro," and she calls him "Wally" – completely flummoxing him.

All in all, this was a pretty fun episode, and it was only frustrating because it felt like the show's been hitting the snooze button on some way more interesting story ideas. Like the impending cracks in "our" universe, the super-weapon, Peter being a lying scumbag, Fauxlivia's baby, Sam Weiss probably being a lying scumbag, the First People, Charlie and Lincoln realizing that Walternate is a lying scumbag, and so on.

The good news is, the promo makes it look like next week's episode will be full speed ahead, with only a couple more episodes after that one. The next few episodes will almost certainly be the crazy ride we've been waiting for. And I, for one, can't wait.