In brief: A messy action/love story heavy on sap and explosions, and lacking in performances.

There's a funny scene in "The Banks of the Lethe" that had me laughing hard. It involves Harper performing for Dylan an experiment on some melons, testing a device that resembles a transporter on Star Trek. This experiment is not entirely successful. When the melons materialize, they explode in a loud BOOM as melon debris goes splattering everywhere. Harper looks on with the zeal of a 10-year-old who just detonated a firecracker inside a model airplane. There's a certain self-aware goofiness in the way these melons are blown up for this scene, and, well, I just found it weirdly amusing. (Yes, I suppose it's not difficult to amuse me.)

Unfortunately, these melons are like a lot of scenes in this episode -- they're on film and they make a big mess. It's also perhaps a bad sign that the melon detonation scene is one of the show's highlights. After making a time-travel episode as compelling as "Angel Dark, Demon Bright," why in the world make another one to rehash the cliche that love conquers all? The odds of successful time travel are said here to be infinitesimal, but you could've fooled me; Dylan has crossed 300 years on three separate occasions now, and that doesn't even count the return trips.

As for love conquering all, it also apparently conquers casting. Dylan's fiancee, Dr. Sara Riley, who was left behind when Dylan was stuck in time for 300 years, is played here by Kevin Sorbo's real-life wife, Sam Sorbo. Her dreadful performance, alas, is one of many things that goes wrong in this episode, which resembles the chaotic "To Loose the Fateful Lightning" in the way breakneck-paced action scenes interrupt story without the necessary cohesion.

Again I ask: Where's the focus? This is an undisciplined story, which begs us to care about a surprisingly trite central love story in between salvos of enemy fire and interminable Trek-style space combat scenes where sparks fly through the sets while the camera shakes and people are knocked off their feet.

As the episode begins, Andromeda has returned to the site of the black hole where "Under the Night" took place, to meet with some alien delegates whose society, the Perseid, will by the end of the episode become the first world to agree to join the resurrected Commonwealth. You'd think that an episode about the first planet rejoining the Commonwealth would be material enough for a meaty story, but that's not the story being told here.

Instead we've got elements from 300 years in the past, which to me is akin to early Voyager episodes doing stories about the Alpha Quadrant -- that is to say, somewhat relevant to the central idea of the show but still something that can seem a lot like a crutch. Especially since this comes so close on the heels of "Angel Dark." Somehow, Dylan is able to send a signal through the black hole, which his fiancee Sara miraculously receives. She's able to do this because she's in orbit around the black hole (in the past) on the starship Starry Wisdom, which is on a mission to try to pull loose the Andromeda from the black hole -- which is apparently destined to fail because, well, Dylan is already 300 years in the future. With this knowledge, Dylan & Co. begin investigating the possibility of sending Dylan back through time.

That's the premise, and the rest of the show is an odd mix of routine elements, chaotic pacing, questionable time-travel paradoxes, and unclear battle events. Under David Winning's direction, Miller & Stentz's script is sometimes a blurringly fast-paced action show marked with uncertainty, and other times an overwrought human drama.

And as I already said, Sam Sorbo is a liability here -- a big one. There are scenes where I was amazed at how weakly portrayed Sara's character was. It might be fun behind the scenes to have a real-life couple playing a fictional one, but the results here aren't the better for it. It might've been advisable to cast a more dynamic actor for the part of Sara; Sam Sorbo's rendition is far too frequently wooden and rings painfully false.

And, as you can imagine, when your central guest character doesn't carry a show -- especially with a role as crucial as this one -- the show stands a good chance of sinking, which "Lethe" does.

Besides, do we really need the flashback scene where Dylan and Sara meet in the middle of a Magog attack? The Meet Cute is a cliche, one that's not mitigated here with much in terms of wit. (Sara: "Admiral Stark warned me about you. She said if I ever met you, I'd end up either falling in love with you or killing you." Yawn. How many iterations are possible in sci-fi on the Han Solo/Princess Leia type banter?)

There's another guest character here, Captain Khalid (Elia Gabay), a mutual Nietzschean friend of Sara's and Dylan's, who provides a sensible example that not all Nietzscheans betrayed the Commonwealth when the war started. Unfortunately, Khalid is largely superfluous and the actor puts in an underwhelming performance; we don't really get much of a dynamic between him and either Dylan or Sara.

Acting in a story like this is key, and when it's not there, it guts the story. The platitudes on love that we get here are ages old, so unless the actors can bring a lot to the table we've got problems. I'll freely admit to buying into a love story when it works as well as, say, DS9's "Chimera," but a story like "Chimera" reveals stories like "Lethe" as all the more hackneyed.

Some events of the story had me scratching my head. The idea is that Dylan will be sent back through time using Harper's grand experiment on new technology, something that resembles a transporter. (It's about here where we get to the exploding melons.) Harper's teleporter plays like a jibe at long-established Star Trek technology, but considering the plot then uses it as a serious part of the story, I feel more like the joke would be on me if I bought into it. Strange, how Harper is good at contriving technology on demand when it suits the given purpose, whether it's Rommie's body in "Lightning," the humongous explosion in "Angel Dark," or now a teleportation device that was apparently beamed directly in from a parallel Roddenberry universe.

Harper is finally able to get the thing to work. Go figure -- the first successful use of the teleporter is with a melon that has the word "Trance" written across it. So even in an episode where Trance doesn't make a single appearance, we still get our weekly dose of Trance Is More Than She Seems. As for Harper, I'd recommend a heavy sedative; Gordon Michael Woolvett goes way overboard with the hyperactivity this week, turning Harper into a self-parodying annoyance.

The plan is for Dylan to go back in time and bring Sara back with him. Anyone who thought this had a chance in succeeding probably needs a reality check. Obviously, Dylan does not explode on camera like those melons when he beams into the past (that would require the end of the series and also a TV-MA rating). But nor is he able to bring Sara to the future with him. Harper is clever, but apparently not quite clever enough. Dylan doesn't stay in the past with Sara because restoring the Commonwealth "is more important than either of us." I must ask: If he really believed that, would he have staked his life on 50-50 odds to go into the past in the first place?

To get us to the more or less inevitable conclusion (which, admittedly, benefits from an occasional nice note of melancholy) the story first turns into a free-for-all, with the Starry Wisdom coming under attack by the Nietzscheans, and then later the Andromeda in the future coming under attack as well. I didn't understand the latter battle. Tyr explains where the enemy ship came from in a sentence that serves as one of the fastest utterances of plot explanation that still nonetheless leaves the whole situation inexplicable. This proves the point that action doesn't work unless it grows organically from the story. As far as I can tell, there's no purpose for this battle except to satisfy the action/explosion quota.

There are also vignettes here that surface quickly and have no follow-through. Like Dylan's backup plan for Andromeda in case he doesn't make it ("Tyr, you know what to do"). And Tyr and Beka pulling guns on each other. What's this about? The story moves too fast to make real sense out of it.

This episode seems sincere in some of its love story details. Kevin Sorbo in particular seems to invest a lot into all aspects of his character's arc, particularly that of his dedication to both his fiancee and the restoration of the Commonwealth. But the episode doesn't execute well and suffers from too many cliches. The details of predestined timeline fate are undercut by the fact that characters seem to think they can still outsmart that fate -- which, given the ship's crucial actions in "Angel Dark," begs the question of what happens to the galaxy if the Andromeda were pulled out of the black hole by Sara's efforts and never traveled back in time in that previous episode.

Forget it. I'm out of my element here. My only consolation is that the creators apparently were too.

Next week: Yep, this must be a Roddenberry show, because our captain stands on trial.

Previous episode: The Ties That Blind
Next episode: A Rose in the Ashes