"I think telling the truth is about as healthy as skidding round a corner at sixty."

"And life's got a lot of dangerous corners -- hasn't it, Charles?"

In "Dangerous Corner," J. B. Priestley's marvelously ingenious suspense play, a casual remark is made at an intimate party of close friends.As a result, the bright, civilized conversation skids around the corner onto the dangerous ground of truth. Before the evening is over, each character has unmasked to reveal secret emotions and relationships within the group.

The Touchstone Theatre Company rounds "Dangerous Corner" with unusual skill and control for a young troupe in its first season. Priestley's play demands style, assured delivery of literate language and ensemble acting from a cast of seven. One false note can destroy the intricate relationships as the conversation runs out of control like a car without brakes.

Priestley's play, first performed in 1932, demonstrates the proposition that a chance comment made at a particular moment can alter the course of lives.

His point is reinforced in the ironic epilogue, a stroke of theatrical virtuosity, in which the characters return to repeat the lines of the opening scene. One sentence remains unspoken. The conversation rounds the dangerous corner and the party goes on.

As the play opens, associates of a publishing firm are gathered for a small party at the English country home of Freda and Robert Chatfield. Among the guests is Olwen Peel, secretary to the publishers.

Freda offers Olwen a cigarette from a musical box that plays "The Wedding March."

"It belonged to Martin, didn't it? He showed it to me," says Olwen as she takes a cigarette and sets off a string of revelations.

As the conversation continues, each character reveals much more than he or she intended or wanted about relationships to each other and to Martin, who presumably committed suicide a year earlier.

Under the sensitive direction of Camilla David, the Touchstone production catches the subtle nuances of language and reaction to Priestley's play. As revelations shift among the characters, the listening actors do not relax as bystanders. Their faces reveal emotions that will surface later.

In the six major roles, there are consistently strong performances from Marcia Gay Harden, Louise Manske, Katherine Leask, Gerry Paone, Bill Whitaker, and James Marilley. Gere Musgrave maintains the quality in her supporting role of the gossipy novelist.

"Dangerous Corner," which runs through July 12 with performances at 8 p.m. Thursday through Sunday, closes the Touchstone Theatre's pilot season in a converted storefront theater at 4246 N. Fairfax Dr., Arlington, at the Ballston Metro stop. A deli-grocery will take over the store and Touchstone is looking for new theater space along the Metrorail line in D.C. and Virginia.