A.R. Gurney has a knack for writing formally inventive plays that are, ultimately, rather conservative.  Love Letters, which recently had a run on Broadway, is entirely epistolary, but the story it tells—about nostalgia, about the passage of time—is affecting but conventional.  Now the Signature is reviving What I Did Last Summer, in which many of the stage directions are projected behind the actors, so as it begins we read, “Before curtain: Music: an old Bing Crosby recording such as ‘Swinging on a Star’ ” before we hear any crooning.  Props are used only when miming is inconvenient.  The fourteen-year-old Charlie (Noah Galvin) walks onstage and announces, “This is a play about me when I was fourteen.”  His mother, Grace (Carolyn McCormick), adds, “This is also a play about me,” before hesitating, “And if it isn’t, it should be.”  And Elsie (Kate McGonigle), Charlie’s put-upon sister, will later complain, “I’ll tell you one thing this play is not about.  It’s not about me.”

Despite this metatheatrical playfulness, What I Did Last Summer is a cozy and familiar story: around the end of World War II, Charlie and his family are staying in a house on a summer colony on the Canadian shore of Lake Erie.  Charlie’s father is in the Pacific, and he divides his time between childish goofiness and playing grown-up, between mooning his mother and sister and driving a car without a license.  He gets work doing odd jobs for Anna Trumbell (Kristine Nielsen), the “Pig Woman” known for her eccentricity and misanthropy.  She pays Charlie in art lessons, lets him drink a glass of wine at lunch, and more generally offers him the kind of encouragement and freedom that can be attractive to a boy who is not quite as old as he thinks.

Mr. Galvin is terrific as Charlie; he has a nice unselfconscious, physical looseness about him that is perfectly suited to a person on the cusp of maturity.  And Ms. McCormick leaves most of Grace beneath the surface; a former student of Anna’s, she has eschewed rebellion for a conventional life and now must perform the role of the ‘forties housewife without betraying her regret to her family.

Like Love Letters, What I Did Last Summer is deceptive in its simplicity; there is nothing new or revelatory about the script, but there is a warmth to it that is not common, either, an understanding of adolescent angst that never devolves into juvenile melodrama or adult condescension.  Late in the play, Bonny (Juliet Brett), a friend of Charlie’s, tells the audience, “Oh God, I’m lying more and more.  Is this what it means to become a woman?”  This is precisely Mr. Gurney’s tone: light, funny, with a twinkle of wisdom, and an itching feeling of the sadness that is soon to come.

What I Did Last Summer runs through June 7th at the Irene Diamond Stage.  480 W. 42nd Street  New York, NY.  2 hours.  One intermission.