This is one of the less convincing psychic dramas in the series, drawn from "human record" (a useful weasel, to free them from the onus of proving that it's a true story). To compensate, however, we get an unexpected star performance from both Joan Fontaine and Warren Beatty as the married couple, however non-existent the chemistry between them, across such a wide age-and-culture gap.
The Fontaine character has become fed-up with herself as the alcoholic wife, forever lamenting the stillbirth of the child he'd declared he didn't want. ("This is your lucky day. The baby died." she'd remarked bitterly, coming out of the operating theatre.) Now she decides it's time for a New Me - divorced and teetotal - as she explains to him on a visit to their mountain cottage. He decides he might as well drive home, but crashes the car in a snowstorm, almost killing himself, with his head pressing on the horn, which blares continuously.
That sound is echoed by another car-crash close to the cottage, and a young man knocks on the door, asking to use the phone (which doesn't seem to be working). When he turns towards her, she faints on recognising a much-younger version of Beatty. As she recovers herself, he starts to tell her his life-story, including the hospital incident, in which he experienced a dramatic change of heart at the crucial moment, suddenly sensing the joy of fatherhood and a pang of regret for the dead infant.
We can't tell you the rest, but we never hear why he couldn't have told her at the time about his feelings in the hospital, which might have encouraged them to try again for a baby, and saved her from years of dreary alcoholism. (Also, the phone seems to be working again!)
Your host John Newland starts with a quite pointless theory about city folk wanting to escape to the mountains and vice-versa, and ends with a rather limp suggestion that the mature Beatty may have sent his younger self up to the cottage to prepare her for his own re-entry into her life.