Nina Leeds - Lynn Fontanne
Charles Marsden - Alfred Shirley
Edmund Darrell - Walter Abel
Sam Evans - Donald MacDonald
Gordon Evans (as a boy) - Peter Griffith
Gordon Evans (as a young man) - Donald Buka
Madeline Arnold - Joan Thompkins

There were a number of problems in adapting to radio what is probably the most famous play written in America. The question of network censorship was not the least of these since, through the years, certain conventions have come about regarding what is and what is not fit for the ears of children (of whatever ages). One of the first problems, then, was to prune judiciously whatever clarity became frankness. Surprisingly enough, the network, once it had accepted the whole, found little fault with any of its parts. I did, of course, use discretion before presenting the script for certification. All references to Nina's extracurricular activities in the hospital had been deleted. Also, eliminated was the fifth and final scene (in the play) of Part One, in which Nina and Darrell rhapsodize over their love and certain amorous events of recent occurrence. This is the scene that ends with Darrell's renunciation and flight to Europe.

The use of Marsden – a writer and a very introverted one at that – as the Narrator appeared as a must before I had got very far in my reading of Part One. He was the only one who knew the complexities of the situation, who could be of it and still outside it. He could tell it, I decided, as though he were writing it – a blurting, long-delayed attempt to find peace for his soul by giving utterance to the truth. When I reached that speech in Part Two in which O'Neill has him say that some day he would write this story – of himself and Nina and the others – I knew I was on the right track.

The probings into the minds of the characters – the asides – presented less of a problem than had been anticipated. There were three possibilities: a filter mike, a musical underlining, a vocal adjustment. We tried the filter but it didn't work. There was something almost eerie about it that detracted from the flesh and blood. The musical underscoring we jettisoned (without trying) as being too monotonous, producing a "Here we go again, boys!" feeling every time Hal Levey raised his baton. The only thing left was the adjustment of the voice – a kind of sotto voice effect that really gave the impression of a person talking to himself – which, after all, was what we wanted.

The direction [Filter] was left in the script as an aid to the actor. No filter was ever used.

Arthur Arendt (Theatre Guild on the Air, H. William Fitelson)