The biggest problem at the core of "Nothing Left on Earth Excepting Fishes" is that I just can't bring myself to care about Ed Mercer's poor broken heart, and the episode really, really wants me to. The second-biggest problem is this episode recycles so many over-worn tropes that I grew restless and bored with stretches of it.
Then there's the ending, which tries with all its might to be simultaneously offbeat and poignant (as a shuttle flies off to Billy Joel), but falls flat because such pretentions only work if there's a workable emotional core beneath the surface. There isn't here, so it feels like an audacious but empty artistic conceit. I'll give Seth and his crew an A for effort, but a C for the end result.
"Excepting Fishes" is also so full of clichéd story beats and subplot distractions that the emotional core feels shortchanged when it isn't being oversold. That's really too bad, because the intentions here are noble and there are moments of intelligence, even if we've seen this territory covered before. Plus there's a cleverness in continuity in the way this episode ties back to last season's "Krill" and how it uses the casting of Michaela McManus.
McManus plays Lt. Janel Tyler, the cartographer who came aboard the ship in "Ja'loja" and sat down for drinks with Mercer at the end of that episode. Tyler and Mercer are now dating, and Mercer decides to take her on a shore-leave trip (but first runs this idea by Kelly, because we simply can't do without Ed/Kelly scenes that induce eye-rolling). Aboard their shuttle, Mercer and Tyler are attacked by a Krill ship and taken prisoner.
What we now know was not a coincidence, McManus also played the Krill schoolteacher Teleya in "Krill." At the end of that episode, Mercer and Malloy killed everyone aboard that ship except her and the schoolchildren. I thought the violence at the end of that episode was glibly handled, so it's nice to see it followed up here with some consequences, although I have my doubts about the specifics. Lt. Tyler, you see, is actually Teleya as a surgically altered undercover agent who is enacting a very elaborate revenge upon Mercer. She stages her own kidnapping along with Mercer and uses herself as a hostage as leverage over Mercer to try to gain Union security codes. It reveals their entire relationship as a setup and a sham. (Naming McManus' character "Tyler" has to be a reference to Discovery's Tyler/Voq imposter arc, which is a cute little elbow jab.)
Mercer is crushed to find out this woman whom he was falling for (and thought was falling for him) was just playing him for a fool. He's so crushed, indeed, he wants answers, and wonders how anyone could be so convincing in a relationship while not feeling anything real. Because it was real to me, dammit!
This could perhaps have sustained the entire episode, but "Fishes" is too impatient and scatterbrained for that. Instead we get a bunch of hacky shoot-em-up action when the Krill ship is attacked by one of their many enemies. Mercer and Teleya end up escaping to the surface of a planet where now they are hunted by other bad guys — although no effort is made to explain what the relationship between the Union and this third party might be, if any. Mercer and Teleya must team up while on the run even though they are sham lovers revealed as enemies.
"Fishes" would have been wiser to focus on one thing, but instead it becomes a hodgepodge. The action is rote and takes up way too much screen time. Meanwhile, there's a B-plot involving Malloy's announced intent to take the commander's exam, which is an oddly placed semi-comic plot happening in between the more serious scenes with Mercer and Teleya. It's yet another example of the awkward tonal swings on this series. It's also another example of this show feeling like warmed-over second-generation Trek leftovers — specifically a rehash of TNG's "Thine Own Self" when Troi suddenly decided she wanted to take up command — but the twist here is that Malloy doesn't even really want to do it; he just wants to be able to tell chicks he's doing it, which is awfully juvenile even for him. The saving grace here is Grayson, who shows a deft touch for leadership through sanity and honest conversation. (This subplot does, at least, contain the episode's funniest line — Bortus' very Worf-like deadpan observation, "He will fail.")
The good intentions here show Mercer trying to reach out for understanding, using evolved
Starfleet Union values to look for common ground and avenues to peace, despite all evidence the enemy is completely unreasonable. And about that: I feel like the Krill are too one-dimensional to be of very much use as the series' primary adversary. They are a monolithic batch of religious fanatics bent on destroying anyone who doesn't worship their god, so Mercer's attempts to show a gesture of goodwill by letting Teleya go may very well be a pointless, even foolish, symbolic gesture.
Of course, the whole point is that we have to start somewhere with our olive branches. But giving the Krill even a millimeter of depth or shading would've made this a much easier sell. As it is, the Krill seem so dogmatic and implacable that the idea of creating "Janel Tyler" with all her simulated empathy and feelings seems beyond their psychological reach. (As Mercer humorously puts it, "I liked it better when you used contractions." But this proves the point; with Tyler/Teleya it's like an A/B switch has been magically flipped, when this scenario seems to call for something more subtle.) Maybe the Krill will get fleshed out eventually (Mercer's comment that they used to be less fanatical before they started venturing into space is a nugget of potentially interesting information), but for now this is limiting.
Here's the thing. I'm inclined to root for Seth MacFarlane and his scrappy desire to turn his fanboy obsessions into a TV show. But the problem is that MacFarlane as an actor has to carry big scenes and complicated emotions in a show like this. Unfortunately, Mercer as played by MacFarlane can never transcend the level of the sorry sap who was stood up at the junior prom and has been snarking his way through life ever since. There's no gravitas to the character because there are no dimensions to the performance. That is fatal for a final scene that wants us to get all worked up over watching the captain's fake girlfriend get sent home with a flash drive full of Billy Joel songs. There's a fine line between brilliant and ridiculous, and "Fishes" ends up on the wrong side of it.