Separation is American Playhouse‘s final new offering of the season, a two-character play first produced on the London stage.

David Suchet, recently a puckish Hercule Poirot on Mystery!, plays Joe Green, a burned-out English playwright. He chain-smokes and thinks he may be agoraphobic.

But this middle-aged failure once wrote a popular play, and an American actress (Rosanna Arquette) writes to ask whether she can stage and star in an Off Off Broadway production of it. Joe Green calls her in New York to give his permission and they hit it off. Separation is primarily a series of transatlantic phone conversations that reveal, among many other things, that Arquette’s Sarah Wise suffers from a rare neurological disease. Sarah hasn’t had any feeling in her feet since she was 13, and gets around on crutches.

Playwright Tom Kempinski sets up an all-too-neat contrast: Joe is an emotional cripple, Sarah a physical one — thus, for the purposes of this drama, they’re made for each other. As Sarah notes, ”Joe, I never met anyone who needed me like you do.” Much of the dialogue is like this; motives are stated out loud; characters talk like therapy patients stretched out on the couch (”I have such rage toward my parents!”).

In an attempt to make these earnest but tedious characters lively, Suchet and Arquette over-enunciate their meager lines and use any excuse to laugh much too uproariously or to break into racked sobs. Their efforts are admirable, but they don’t help much.

American Playhouse, which presented a number of first-rate shows in the past few months, ends its season with the sound of two people yammering.