Act II Playhouse's production of Ernest Thompson's On Golden Pond marks the fourth time the actors have been paired as husband and wife (including turns as Linda and Willy Loman in the Arden Theatre's 1996 Death of a Salesman). Considering their easy rapport, the sweet-and-sour balance of Belver's plucky Ethel and McCarthy's dyspeptic Norman Thayer, it's as though the actors have gone and made it official.

How convincing are they?

When Belver and McCarthy sit side-by-side in an intimate chat - enveloped by set designer Dirk Durossette's rustic wooden cottage, and lighting designer James Leitner's soft afternoon light - one imagines they'd still be here having the same conversation even without an audience. Their bond is as warm and comfortable as the knitted blanket thrown over the back of their sofa.

Sure, that's the whole point of live theater, to transport and transcend, but rarely, if ever, does this transcendence feel so natural.

Belver and McCarthy's success has less to do with Bud Martin's direction than with their obvious affinity. When other characters appear at the door of the Thayers' Maine summer retreat - including estranged daughter Chelsea (Megan Bellwoar); Chelsea's boyfriend, Bill (Carl Granieri); Bill's son Billy Ray (Peter Balcke); and Chelsea's childhood flame Charlie (Tom Byrn) - we suddenly notice the acting. It comes as an unwelcome intrusion.

If this is intentional - an illustration of how the Thayers fortify their marriage from the inside, fending off potential invaders, including their offspring - it works. But it does so only at the expense of the supporting characters.

Act II will most likely have to battle the perception (probably based on the memory of the 1981 film) that On Golden Pond is a real downer. The thing is, it's not.

Thompson's writing is charming. And whenever the script looks ready to veer into sticky or maudlin territory, Norman or Ethel parries with a sharp retort.

The play's pleasures are slightly old-fashioned: The experience is akin to driving down a New England road and happening upon an antique shop laden with hand-embroidered napkins and midcentury children's toys. There's sadness among the detritus, but also delight. There are even some real treasures. This production puts its treasures center stage, and though they might not be as shiny as current tastes dictate, perfectly synced performances like Belver's and McCarthy's are pretty darn priceless.

On Golden Pond

Playing at: Act II Playhouse,

56 E. Butler Ave., Ambler.

Through Sunday, Dec. 13.

Tickets: $25 to $30.

Information: 215-654-0200

or www.act2.org.