The problem with "Tigh Me Up, Tigh Me Down" is that the tone is all over the map. I mean, this episode is absolutely everywhere -- drama, comedy, paranoia that too quickly dissolves -- and it doesn't find an adequate through-line. This is the season's most erratic episode in terms of both writing and directing, with a net result that lands somewhere in the realm of watchable confusion. It's the weakest outing of the season. What's reassuring is that even the weakest episode of Battlestar to date still proves tolerable and has its share of redeeming qualities.

This episode is basically about two things: (1) Roslin suspecting Adama of being a Cylon, and (2) everyone suspecting Ellen of being a Cylon.

Who's Ellen? Glad you asked. Ellen Tigh (Kate Vernon) is Colonel Saul Tigh's estranged wife, presumed dead in the initial Cylon assault, but who turns up here, having been lying comatose on the Rising Star after a narrow escape from the Picon airport. The suddenness of Ellen's appearance is jarring in narrative terms, but at least the characters also find it jarring, and Adama suspects she might be a Cylon. Tigh is happy to see his wife again, and Ellen talks with him about making a "fresh start," which might be just the personal jolt Tigh needs. (An earlier scene shows a self-disgusted Tigh pouring the last contents of his liquor bottle into a trash can, about which he says to himself, "Well, at least I did that much.")

Meanwhile, Roslin -- with her own suspicions piqued by Leoben's paranoia-inducing allegation that Adama is a Cylon (see last week's "Flesh and Bone") -- suggests that Adama be the first to undergo Baltar's new Cylon-detecting blood test. The test requires hours of processing and can only be performed on one individual at a time, much to Baltar's dismay; he has 47,905 tests to conduct if he's going to test the entire fleet. To pass the time, he has imaginary Six sex in the lab, which leads to a masturbation scene that is admittedly funny (Kara walks in on him) but is an aspect of the character that is really beginning to wear thin.

I'm not sure what to make of Roslin's suspicions of Adama. The lesson ostensibly learned in "Flesh and Bone" was that the Cylons want to use our paranoia against us. Isn't Roslin's willingness to give credence to that paranoia in fact playing right into their hands? That in itself isn't really a storyline flaw so much as how the episode ultimately plays out this element of the story with a comic non-payoff (more on that in a moment).

As for Ellen, whether she's a Cylon or not, the one thing the story makes clear is that she's trouble. Tigh and Ellen were clearly longtime partners in alcoholism, and there's a scene here where she breaks out the booze and makes a toast to "starting over." It seems to me that their problems in the past were probably caused at least partially by the booze, so their drinking to a fresh start isn't particularly promising.

At dinner with Adama, Roslin, and Lee, Ellen gets hopelessly sloshed while Tigh laughs along (they play the role of each other's enablers) as the rest of the dinner party smiles politely. Ellen runs her mouth, calls Adama "Bill," and plays footsy with Lee under the table. If there's credit to be given for this episode, it's that it doesn't waste any time establishing Ellen as a shameless flirt and a negative influence to Tigh's professional life.

Still, how much is too much before Ellen's obnoxiousness becomes more than the audience can stand? I propose the clock runs out with the scene where Ellen hangs from a scaffolding while putting her legs around Tigh's head. Baltar shows up, and he/Six sees something about Ellen that arouses his suspicion. Is she a Cylon?

Up to now the episode is a muddled mix of suspicion and drunken behavior. The episode's definitive breakdown comes with the "payoff" scene in the lab, where Baltar is asked to first run a Cylon test on Adama (Roslin's request) and then on Ellen (Adama's request), and then all the threads crash into each other with everyone arriving in the lab and arguing. The scene is played as screwball comedy, but that's a miscalculation. There's simply nothing funny about the idea that these people are suspecting each other of being Cylons. Going to such a place should be sad, or scary, or painful, or insulting -- anything, really, but funny. This proves to be a very odd -- and unworkable -- choice. The characters -- especially Roslin after airing suspicions about Adama, of all people -- back away from and are let off the hook of their paranoia far too easily.

And the comedy itself doesn't segue well into the rest of the episode, which jumps from humor to foreboding to action without a clear idea of what any of it means. There's a subplot involving an erratically behaving Cylon Raider, and the way this subplot figures into the story feels like an underdeveloped distraction. There are also the usual scenes involving Boomer and Helo on the run on Caprica, the only point of note being Boomer's suspicion that she's now being hunted as a traitor by her own Cylon co-conspirators.

Still, for all its lack of coherence, the episode has scenes that work, like the pleasant Billy/Dualla romantic scene where he gently pumps her for information until she calls him on it. Or the fact that Baltar's Cylon test seems to pass everybody. Or the revealing moment where Six on Caprica shows a pained look of apparent envy for Boomer's ability to so easily fall in love with Helo, even as Six labels Boomer "pathetic." Clearly, there's a sense here that the Cylons want to know what it is about love/sex that contributes to making humans tick.

These moments add to the canvas of the series, but the episode itself is a puzzling tonal mishmash.

Previous episode: Flesh and Bone
Next episode: The Hand of God