Carey Mulligan Is Perfection in a Play That Isn’t

That’s just one way of advising playgoers to be on their guard at “Girls & Boys,” the solo play from the Tony Award-winning writer Dennis Kelly (“Matilda”) that finds the performer Carey Mulligan in cheerfully chatty mode — for the first stretch, at least. The production, which runs through March 17, brings Ms. Mulligan, an Oscar-nominated actress, back to the Royal Court Theater for the third time.

Ms. Mulligan’s unnamed character is dryly funny on any number of topics, from the vagaries of fate (“I got Southampton,” she says with regard to picking a travel destination at random) to airport etiquette and a job interview that she recollects in painstaking, bitterly comic detail, throwing in a fart joke for emphasis. It’s easy to imagine knocking back a beer or two with her and emerging chums for life.

Listen carefully to her words, however, and you may notice an underlying aggression. At that interview, for instance, Ms. Mulligan speaks of her potential employer “sizing me up, like a psychopath weighing up which ear to cut off first.”

So it’s not a complete surprise when events take a shivery twist. (There are also hints in the director Lyndsey Turner’s ultraslick production, and in the thanks proffered by Mr. Kelly in the published text to Euripides, among others.)

For much of the time, Ms. Mulligan stands before us, like a chicly coifed if barefoot comedian eager to corral an expectant audience. Those scenes are interlaced with domestic encounters with two children, who remain unseen but nevertheless seem to demand every reserve of energy that this quick-witted, expletive-prone woman can muster.

The vignettes draw upon Ms. Mulligan’s unheralded gifts as a mime artist — suddenly, she must play an entire family — and come with a visual commentary: At various moments, the set from Es Devlin crackles into brightly vivid life, only to revert in an instant to the neutered, anesthetizing look that pervades throughout. (Ms. Devlin and Ms. Turner, the director, are frequent, and invaluable, collaborators.)

Visual contrast is missing from this landscape. Something else is missing, as well, though to elaborate would result in an unforgivable spoiler. What can be said is that the Ms. Mulligan we see at the close of the uninterrupted 90 minutes has an altogether different aspect from the freewheeling raconteur seen at the start. Rather like the American playwright Neil LaBute, who has traversed comparable terrain in such plays as “Bash: Latter-Day Plays,” Mr. Kelly addresses humankind’s capacity for violence at every turn. Not even the children are exempt.

So far so good, if so depressing, though hardly more so than the world at large. But not content to leave well enough alone, Mr. Kelly dresses up his narrative in ways that detract from its power, like some overzealous puppeteer. More than once, there is the sort of rhetorical question — “Does that make sense?” — that in the theater tends to make me queasy, lest an overeager audience member reply. And I’m not sure we need the reminder that this grievous tale represents only one side of the story. Since when did the theater become a courtroom requiring equal time for all?