In brief: Some exceptionally good and believable character work, with an ending that falls a bit short.

"Lineage" is just about a perfect little straightforward character show for four acts before settling for some oversold melodrama at the last moment. For once, everything seems to be clicking -- the dialog, the characters, the acting, the directing, the editing. The ending pushes too hard, but I guess you can't have everything.

Keeping in tune with what I hope is a final-season trend (evidenced this past fall by the marriage in "Drive"), this is an episode that shows the writers actually committing to a change in some of their characters. B'Elanna learns that she is pregnant, much to both her and Tom's surprise; despite their attempts, they weren't expecting to beat the odds against Klingon/human conception. But Doc has good news: B'Elanna is pregnant with a healthily developing baby girl.

Once this information floats around the ship, everyone is offering their advice on parenting. One theme Voyager has often pushed is one of a ship-bound "family." That's sort of the way it works here, with B'Elanna and Tom taking in information from their shipmates, the extended family that exists where traditional family cannot because of a 30,000-light-year separation.

One thing "Lineage" gets very right is its single-minded focus on what's important. This is a B'Elanna and Tom show, and the script demonstrates that it's aware of that fact. Compare this to "Shattered" last week, which wanted to be and could've been a standout Janeway/Chakotay show, but wasn't because the story was such an over-plotted mess with umpteen unnecessary characters. This time the writers get it right; the plot is straightforward and the story runs with characterization and decision-making. There are no unnecessary twists or distractions. With a premise that probably could've taken about a hundred obvious wrong turns, "Lineage" has the courage to take none of them.

Take, for example, the interaction between the characters, of which there is plenty. There's a short scene here between Paris and Tuvok. It's a scene that makes a great deal of sense and works because it respects the characters and the sincerity that would likely arise from such a discussion. Without being an ultra-serious message moment, this Paris/Tuvok scene manages to avoid poking any obvious jokes at Tuvok's overly serious Vulcan sensibility -- something this series has had a tendency to do. Instead, it remembers that Tuvok is a parent and simply has Tom take the prudent action of asking for Tuvok's advice. The scene ends with a nice Vulcan-like line of advice about raising children. It's an effective line because it reveals the truth in the characterization and is played with a note of simple pleasantness and sincerity.

Or take the Janeway scene, once the show's main conflict between Tom and B'Elanna arises. B'Elanna wants Janeway to act as captain in a personal disagreement. Janeway will not. She tells them they must work it out themselves. Her dialog is level-headed and fair. Good for her.

Or take the Harry Kim scene, where the writers have him say just enough without saying too much. Harry knows to help out a friend and give him some advice. But he knows when to pull back and stay out of things, simply telling Tom that until B'Elanna cools down, "My couch is your couch."

Why are Tom and B'Elanna in disagreement? That's actually where the core of the episode becomes evident: B'Elanna wants to tamper with her baby's genes and remove Klingon biological traits, like redundant organs. This would also have the effect of giving the baby a human appearance. She argues her position to the Doctor by saying her baby's health would benefit and is the primary issue, but Tom sees right through this argument and calls her on it flat-out: "You don't want her to look Klingon."

He's right, though it goes much deeper than that. "Lineage" has a flashback structure to it that goes back to B'Elanna's childhood. The flashbacks reveal a young B'Elanna (Jessica Gaona) at an age where her headstrong adolescence began crashing into her father's (Juan Garcia) own doubts about his shaky marriage. This comes to light gradually, eventually revealing that B'Elanna blames herself for the dissolution of her parents' relationship. As a child, she said and witnessed things at a time that would shape certain opinions for life.

Now she hopes to keep history from repeating (she fears her Klingon side and the possibility that Tom, like her father, might not be able to deal with it), though getting her to admit the full truth is like pulling teeth. One thing I've always liked about B'Elanna is that she's got that element of self-torture and fallibility. She's flawed. She's perhaps the series' most complex character, and an episode like "Lineage" shows why. She goes to extremes here that eventually seem beyond any reason, except for that self-torment we know is there. She manipulates the situation -- in ways that quite frankly seem to me as potentially relationship-damaging actions. Tom's cool head and ability to listen is admirable. He's upset but understanding that B'Elanna takes things so far, which she does here by altering Doc's program just enough to make him believe the gene alterations are in the baby's best health interests.

For B'Elanna's character, this plays as a sort of companion episode to last season's "Barge of the Dead" (still one of favorite Voyager outings). It's like the flip side; last year we learned about her mother, and this year we learn about her father. In the middle has always been B'Elanna, a character torn between two very different cultures and, I suspect, not completely comfortable in either. In addition to bringing up interesting ethical questions about genetic manipulation, B'Elanna's actions also play on the issue of self-sensitivity along racial or cultural lines: How exactly do some of us fit into groups when we feel as if we must "choose" one over the other and don't automatically fall into one or both? The answer, of course, is in asserted individuality --while not denying who we are. B'Elanna is a character who has coped with an identity crisis probably all her life.

As good as "Lineage" is as a character outing, it falls a little bit short with an ending that I found just a bit too melodramatic. Dennis McCarthy goes overboard with the violins while B'Elanna's tears come flowing, and the whole thing becomes a tad maudlin. It's credible given the depth of B'Elanna, and even effective to a degree, but for my tastes it seemed to be pushing it in trying to punctuate the Moment of Truth.

No matter. "Lineage" is one of Voyager's best-characterized episodes in some time, showing a cast that comes across as well oiled and execution that for the most part is flawless. It's not the sort of sci-fi/action outing that many fans of the series may hope to get, but it shows the creators of this series still know how to tell good, truthful, understated stories about their characters.

Next week: Interstellar convicts take Voyager hostage and hold a knife to Seven's throat. Don't just stand there and take it -- assimilate his sorry ass!

Previous episode: Shattered
Next episode: Repentance