What happens when the Earth is in a collision course with a meteoric ball of ice and dust, when we face the end of the world as we know it? That’s what playwright Peter Nachtrieb explores in his clever, well-crafted and witty play boom, which opened the third summer of offerings at Brown’s Leeds Theatre. The show is part of the Brown/Trinity Playwrights Rep, which showcases writers with a Brown connection and actors from the Brown/Trinity Consortium.

Nachtrieb, a Brown grad who majored in theater and biology and is now based in San Francisco, tackles the question of what it would be like to be the last humans on Earth, but does so with a fresh, funny and sometimes poignant take.

There is Jules, the nerdy biologist who predicts the end of civilization by observing fish who hide and die in coral reefs. He takes out a couples ad and lures Jo, a budding journalist, to his underground and well-stocked lab. Jo thinks she is there for a night of steamy sex. Jules, realizing a comet is about to smash into Earth, needs someone to repopulate the race.

He figures they’ll be holed up for a couple of years at least before the world is habitable again and he’s not interested in wasting anytime with Jo. The thing is she’s not attracted to Jules, who has tried all sorts of ways of impregnating her.

Then there is Barbara, a sort of Wizard of Oz character who plays the timpani and tosses switches on a control panel every time Jo faints. She offers a running commentary of sorts on the goings on in the lab, an outside observer who is here to tell us the tale, and even lapses into an elaborate account of her own conception.

Barbara, who wears a name tag, can be a little annoying at times. She has a habit of not finishing sentences and digressing in the extreme, but she’s also what makes the play so quirky and off-beat.

Nachtrieb, who just won the $25,000 Steinberg Award for his Hunter Gatherers, has a real knack for the unexpected and a gift for the snappy phrase.

Jo has answered Jules’ ad for a class assignment. She’s interested in casual sex as the “last glimmer of hope for a decaying society.” And besides, she says, the assignment is due Monday.

Jimmy King, a second-year student in the Brown/Trinity Consortium, is fine as Jules, the neurotic, high-strung scientist who never really seems to know what to do with Jo. This is no traditional love story. Jo and Jules wear away at one another. She in fact breaks his leg in retaliation for his advances.

But they do share their own survival, their fleeting life together in the last glimmerings of humanity.

Susannah Flood, who was so solid in Our Town on Trinity’s main stage this past season, gives us a feisty, yet vulnerable Jo, who shows up at Jules’ lab in an ice-blue wig looking for some action. It’s only later that we learn she’s a virgin.

Flood gives a controlled, confident portrayal, full of complexities and contradictions.

Constance Crawford plays the dry-witted, sardonic Barbara to a tee.

boom, directed with a sure hand by Ken Prestininzi, runs through tomorrow, and Aug. 3 and 4. For information and tickets, call (401) 863-2730.

cgray@projo.com