The British are different from you and me.

That might be the moral, such as it is, of "Separate Lies," a psycho-emotional thriller in which three members of the English upper class behave terribly well when they find themselves in a spot of trouble involving adultery, manslaughter and all manner of deviltry. In Hollywood's hands (think "Unfaithful"), this would feature steamy sex scenes, Oscar-worthy histrionics and at least one instance of someone avenging his honor with a gun.

But "Separate Lies" is very British indeed, meaning it's all about restraint, good taste, discretion and tact. Julian Fellowes, best known as the man who wrote the marvelous "Gosford Park," makes his directorial debut in a production that fairly bursts with restraint and good taste, not to mention discretion and tact. Mendacity and avarice may form the toxic heart of the story, but they've been nearly obscured by the polish of good housekeeping, stiff drinks and flawless manners.

"No life is perfect," says James Manning (Tom Wilkinson) by way of introduction in "Separate Lies," and as the high-powered London attorney kisses his pretty wife, Anne (Emily Watson), goodbye on their posh doorstep, it's clear that only carnage can ensue. And ensue it does, in the person of one William Bule (Rupert Everett), whom James and Anne meet that weekend while at their country house.

Some very bad things happen. Through it all, James and Anne and Bill retain what can only be described as the detached civility peculiar to the British upper classes. The chilly matter-of-factness with which they deal with the unspeakable has the air of imperial entitlement about it; they exert the same offhand power as the men who once carved up great chunks of the globe over brandies.

In the end, it doesn't amount to much, but for fans of distinguished character actor Wilkinson, "Separate Lies" will remind them of his tour de force performance in the 2001 drama "In the Bedroom." He delivers a similarly complicated performance here, one in which whipsawing emotions compete with decorous restraint. (Admirers of Everett, on the other hand, will barely recognize the handsome actor, who here has the ropy, hooded look of an emaciated Matt Dillon.)

Fellowes shows promise with "Separate Lies," which he adapted from the novel "A Way Through the Woods," by Nigel Balchin. It may not be nearly as scintillating an outing as "Gosford Park," but Fellowes has brought intelligence and control to the eternally vexing question of whether the right thing is always the good thing.

Separate Lies (85 minutes, at area theaters) is rated R for profanity and sexual references.

Emily Watson and Tom Wilkinson, as an upper-crust couple, share a tender moment in the thriller "Separate Lies."