A lineup of short plays demands the balance and momentum of a musician’s set list. Segues have to be smooth, breaks need to feel natural, the peak shouldn’t come too soon, and, of course, every piece on the list has to be good: no duds. In series A of its 30th annual marathon of one-act plays, the first of three programs in the festival, Ensemble Studio Theatre gets all of that just right.

An upright piano plays as the lights go up on Willie Reale and Patrick Barnes’s three-song musical, “A Little Soul Searching,” in which a pair of souls in limbo (Michael Potts and Karen Trott), who have traveled through life after life as brother and sister, resist being sent back to Earth. It’s a charming entertainment, and a pleasure to hear a couple of Broadway veterans singing, apparently unamplified, in a chamber piece.

Amy Herzog’s “Christmas Present” finds a neurotic, awkward New Yorker (Julie Fitzpatrick) following her shaggy, sweet one-night stand (Jake Hoffman) out to the living room the morning after, seeking his contact information in case of pregnancy or STDs. It is probably the most neatly conventional of the evening’s plays, but it is also smart and surprising.

The first half of the program ends with Michael John Garcés’s “Tostitos,” a vicious, violent slice of life, set in the parking lot of a doughnut shop in a rough urban neighborhood. Red (Andres Munar), a sociopath in his early 20s, is busy wasting some time there with his friend, the belligerent Annie (Jenny Gomez), when they’re joined by Tanya (Karen Eilbacher), an eager 15-year-old. Cocky and cruel, Red plays the two females off each other, charming and bullying them as his mood dictates.

Precisely observed and finely acted under the direction of May Adrales, “Tostitos” is so potent in EST’s small space that it can be difficult to watch. It is also bereft of hope: Growth and forward movement are nowhere to be found. That stasis, whether or not it is part of Mr. Garcés’s point, is the reason this play feels less like a self-contained miniature than a fragment of a larger piece.

“An Upset,” a fast, furious, and fun-to-watch comedy in three scenes, occupies most of the program’s second half. Beautifully crafted by David Auburn, whose work has been largely absent from the stage since he won the Pulitzer Prize in 2001 for “Proof,” it follows the arc of a young Romanian (Matt Lauria) on his way to tennis stardom and an American icon (Darren Goldstein) whose career on the court is coming to an end.

Shades of David Mamet (the play’s second line, “F— you,” is an indication of dialogue to come) and the Kevin Costner-Tim Robbins dynamic in “Bull Durham” give way to a more distinctive chiaroscuro. Ambition and ego, cynicism and romanticism, mortality and vigor rub up against each other in locker-room dialogues that are explosive and poignant by turns.

The program ends with Quincy Long’s “Wedding Pictures,” a farce with one door and a violin. The violin, played by the game and excellent Heather Sommerlad, is key; in sensibility, this is a silent movie translated to the stage, with music setting the tempo and conveying the mood behind all the mime and big emotions on display. The plot is simple and silly: A bride (Autumn Dornfeld) and groom (Eric Gilde) are at the altar when the groom’s lover (Jacob Hawkins) arrives, sending the bride into a fit of tears and the groom into a panic. Ridiculousness ensues.

It’s an imaginative, lighthearted finish to a high-quality quintet. Here’s hoping that the marathon’s series B and C are as good.

Until May 31 (549 W. 52nd St., 212-352-3101).