Ensemble Studio Theatre’s 2008 marathon of one-act plays isn’t a trilogy, of course; no single theme unites the grab bag of works on any of its three programs, let alone in the festival as a whole. But as in many a trilogy, the second of the three parts shows signs of weakness. Series B of the marathon involves rather a lot of slogging between moments of fierce engagement — and in this case, the ferociously pitched battle that is the high point arrives in the middle.

That apex comes courtesy of the marathon’s biggest boldface name, Neil LaBute, whose caustically funny “The Great War” finds him in, of all things, Albee mode. In their austerely affluent living room (all sets are by Maiko Chii), a man (Grant Shaud) and a woman (Laila Robins) sit at opposite ends of a pristine couch, cold and furious, nearly immune to each other’s insults and anger. After nine years of constructing the hell they call their marriage, they are settling the details of its dissolution over cocktails at the home he’s moved out of.

He hasn’t entirely given up on them — he even slips and calls her “honey” — but her every utterance drips with contempt for him. When he suggests that they might give their marriage another shot, she laughs in his face, then eviscerates him: for reading USA Today, for possessing substandard table manners, for being barely acquainted with their children. “Honestly,” she adds, “I don’t say any of that with malice.”

The issue of child custody, unlikely fodder for laughs, yields them nonetheless in a crucial twist that gives Ms. Robins even more cause to savor a delicious role. Under Andrew McCarthy’s direction, with Mr. Shaud playing straight man, Mr. LaBute’s malevolent romp is a great deal of fun.

The conflict at the center of Lloyd Suh’s “Happy Birthday William Abernathy,” the play that begins the program, is generational. The title character (Joe Ponazecki) is turning 100, and his great-grandson, Albert (Peter Kim), has been charged with collecting him from his bedroom and taking him to the family celebration. Problem is, the paterfamilias is a white man and a casual bigot, and his descendants are Korean-American. “I don’t know how my family got to be so Oriental,” he mutters. “I used to be an Irishman.” The play has big things on its mind — racism, the sins of the fathers — but it bogs down in emotionally dishonest moralizing that leaves its actors stranded.

In Anne Washburn’s charming “October/November,” a pair of young New Yorkers, a 16-year-old girl (Amelia McClain) and a 13-year-old boy (Gio Perez), dream toward the future and puzzle out the present. She is loquacious, pushy, romantic, given to making grand declarations (“The recorder is an instrument for elves”) and kissing him simply to get a reaction. He is quiet, thoughtful, eager, just beginning to take shape. Mr. Perez has a lovely moment when, after one of those kisses, he springs to his feet to give a monologue, a boy suddenly bursting to speak. Each of the teenagers is spending the autumn waiting for something to happen. Nothing much does, but such is adolescence, and there’s lyricism, humor, and a visceral understanding in Ms. Washburn’s snapshot of it.

A winningly surreal bagatelle, David Zellnik’s “Ideogram,” begins the program’s second half. Jasper (Bryan Fenkart) is a stockbroker who makes, for his Chinese-American friend Drew’s birthday, a card covered with “make-believe Chinesey writing.” But Drew (Pun Bandhu) informs Jasper that it’s real Chinese, and that it says something. Jasper doodles some more, and soon an elderly Chinese woman (Siho Ellsmore) is interpreting his writing and bringing him tidings of it: “Good news!” she says. “Your play is a success.” This is monkeys typing Shakespeare, except that it turns political and dark. “Ideogram” is something of a tease, with the shift in tone that it doesn’t quite commit to, and the ending that comes too abruptly. But it is an appealing oddity.

The plot of Taylor Mac’s high school comedy, “Okay,” suggests it has the potential to be one as well: Stephanie (Susannah Flood) has just been named prom queen, but she’s busy giving birth — or, it seems, straining not to — in the bathroom as the festivities go on outside.

Hidden in her stall, she listens to her classmates chatter and hook up and rant as they drift in and out of the girls’ room, each of them going on for far too long. Unfortunately, we are trapped in that bathroom with her, and we have to listen to their banalities, too. Ms. Flood is impressive in a highly physical, nearly nonverbal role, half-crouching atop a toilet seat for nearly the entire play. But that feat is largely what the piece has to offer.

Until June 20 (549 W. 52nd St., between Tenth and Eleventh avenues, 212-352-3101).