THEATRE VERTIGO'S recently opened boom contains a cautionary tale that'll put you off online personals forever: A biology student named Jules (JR Wickman) meets a young woman on Craigslist, and invites her into his basement lab. The woman, Jo (Brooke Fletcher), is keen to consummate their casual encounter—but it soon comes out that not only is Jules gay, but he's convinced that a comet is going to hit the world in a matter of minutes, killing all life on the surface. Jules is prepared to take refuge underground for two years or more; his lab has been converted into a comet shelter stocked with food, water, booze, and... diapers? That's right: Gay or not, Jules is planning to repopulate the planet, with a little help from a woman he met on the internet. Jo, meanwhile, is understandably dismayed to find herself trapped in a basement with a man whose only interest in her is as a potential savior of the human genome.

As this scenario unfolds, a woman (Heather Rose Walters) stands on a platform downstage, adding sound effects and manipulating lights. It's not initially clear what her function is, but as the show unfolds, she'll prove to be of crucial importance to Jules and Jo—and to the success of the production as a whole.

Playwright Peter Sinn Nachtrieb has outsized ambitions. What begins as a casual-encounter-gone-wrong is soon revealed to be a self-referential examination of the origins of life itself. Crucially, though, the script is funny (when Jules is asked how he knows he's gay, he responds, "The non-randomness of erections"), and Nachtrieb never allows his weighty themes to get in the way of a punchline.

Wickman and Fletcher are recent additions to the Vertigo ensemble, and boom is at its weakest when they're asked to carry it. Fletcher, in particular, struggles with her character. As written, Jo's ferocious, but Fletcher imbues her with a static, one-note anger, a display of sustained hostility that fails to permit the existence of other more complex emotions. It's overkill—Fletcher shouldn't have to strain so hard to render unlikeable a girl whose favorite word is "motherfucker." The show doesn't really hit its stride until about the halfway mark, when longtime company member Walters takes on a larger role. Walters is perfectly attuned to the script's curious blend of pragmatism and poignancy, and the show's audacious second half more than makes up for the weaknesses in the first.