John & Jen drew a standing O last weekend at the Eagle Theatre in Hammonton, N.J. On a snow-squalling night with the temperature in the teens, it was the warmest thing for miles. It continues through April 9.

An Off-Broadway favorite with a 20th-anniversary revival in 2015, John & Jen is a two-hander musical about a woman's relationship with her brother (with whom she grows up in a household shadowed by a war vet father's violent anger) and, later, with her son. Covering about 40 years, 1950-90, it is very emotional. The Eagle Theatre's ads suggest it has a feel like the TV show This Is Us, and, for better and worse, it does, painting large the characters' loves, losses, hopes, aspirations, and disappointments, working the emotions hard, dealing in unashamed nostalgia and sentimentality.

It is usually played black-box style, that is, bare stage with only central lighting, but coartistic directors Ted Wioncek III and Ed Corsi (who also run the Eagle) and scenic/lighting designer Chris Miller have created a cozy, picturesque attic loft, rich with familial objects -- a Mickey Mantle bat, a baseball, a teddy bear, a clothes rack, a scrapbook -- to symbolize the stages of growing up, or not. In the first act, history flickers in the window and the picture frames: the Beatles arriving in New York, the Vietnam War, Woodstock. Prefatory period pop -- "Lucy in the Sky with Diamonds," "Spill the Wine," "Fire and Rain" -- chimes in.

These choices extend the production's scope, especially in that first act, which is much the superior in emotional and musical effect.

Kimberly Suskind as Jen and UArts grad Adam Hoyak as John are powerhouses. They are the great reason to see the show.

Suskind belts out a soprano not unlike Kristin Chenoweth in certain ranges, with a way of squiggling notes up her nose to indicate irritation. Hoyak excels as the little boy bounding about, wired to meet Santa (and, later, very much not wired), wondering, wanting to live it up, and, later, as a young man squirming under a mother's overprotective hug. He's also great with a comic song, especially "Trouble with Men" and "Little League."

Each swears love repeatedly; each is unconsciously selfish. Each tries to protect the other from hurt.

Suskind scores as the unbearable baseball mom, flipping off wayward umps and embarrassing her son, who's out at home. Hoyak scores as the son in need of heroes. It doth pull on the heartstrings too much; all is warmth, and forgiveness is ever sure. The performers are great, but this show could be tougher by half and still get the standing O.

It certainly scores some hits lyrically. Early on, Jen sings to baby John that "the people who love you the most are also the ones who make you cry," and that "I don't know how it works … somehow it's all right when someone big hits someone very small." She urges him to "play baseball as long as you can." As the two go different ways, she a hippie, he a soldier, they come back together to sing, "I should never have let you out of my sight."

But, again, the first act is a compact, finished whole, while the second seems diffuse, less interesting, unable to follow the stunning close of Act 1. I did like the uneasy end of Act 2, when the boy offers to deny himself a future and stay with his mother, unaware that she is quite ready for him to leave and let her be free. Thanks to Suskind and Hoyak, John & Jen succeeds, and when they leave that cozy attic, we're sad to see them go.

John & Jen. Through April 9 at the Eagle Theatre, 208 Vine St., Hammonton, N.J. Tickets: $30-$40. Information: 609-704-5012,