British playwright Lucy Kirkwood’s 2016 play “The Children” is a work that is simultaneously contained and expansive. It is contained in that the entire play consists of one long scene, unfolding essentially in real time, and it is expansive in regard to the complex ideas it explores.

Jarrott Productions’ intimate new mounting of “The Children,” running through May 12 at the Trinity Street Playhouse, fully exploits this dichotomy. The play is set entirely in a small British coastal cottage owned by a married nuclear physicists Hazel and Robin, on an evening when they have been visited by an old friend and colleague, Rose, whom they haven’t seen for almost 40 years. As the visit unfolds, we learn about Rose’s reason for coming to see them after so long and how it’s related to the catastrophic meltdown of the nuclear plant at which the three used to work.

The biggest flaw of “The Children” is that it takes almost half of the play to get to the reason why Rose has shown up on Hazel and Robin’s doorstep. The proposition that she then makes has such rich, interesting dramatic potential that it is a shame that Kirkwood doesn’t spend a longer time exploring it. The heavy lifting in getting to that turning point, then, falls on the play’s cast, and at this they excel.

Katherine Schroeder, as Hazel, and Pamela Francesca Christian, as Rose, make for a wonderful pair, playing off of one another with completely contrary personalities that lead to equal amounts of angry frisson and deep-seated affection. Just as Schroeder shows how Hazel’s outward neuroses lay atop a deep inner strength, Christian portrays Rose with a quiet strength that we ultimately find is teetering on the edge of great despair. David Jarrott, as Robin, serves as yet another contrast, with an outward vigor and playfulness that comes up against the serious sides of both women. Jarrott and Schroeder are particularly delightful when displaying the nuances that show how they have come to function as a unit over the course of their long marriage.

Though these three dynamic performers do the lion’s share of carrying the play to the point of Rose’s proposition, from that moment on Kirkwood’s complicated, probing script becomes the star. Director Carlo Lorenzo Garcia notes this change by hanging that moment on the precipice between night and day, a slow change of lighting and tone that is achieved with masterful subtlety by lighting designer Alison Lewis.

In exploring the dramatic potential that then arises in these three relationships, “The Children” quickly transforms from a play about these three particular characters into a wider exploration of universal themes that question exactly what older generations owe to the young. Kirkwood’s story directly asks the audience what we might be willing to sacrifice in our lives of privilege, and it comes to no easy conclusion.

“The Children,” then, is a study in contrasts — between characters, personalities, levels of privilege and how much people will sacrifice for their own children, both literally and metaphorically. In centering all of this complexity on three natural, moving performances, Jarrott Productions’ new version of the play is a thought-provoking exploration of vital questions and accusations that we all must face in a world heading closer and closer to disaster.

(This story has been updated to correct a character's name in two places.)