If fashion and Mediterranean scenery tend to dazzle you about a movie then you'll likely be all up in the clouds dancing over this one. For the rest of us who desire somewhat more from our hours invested in a movie, In-the-Cool-of-the-Day falls far short of the mark I'm afraid.
It's your basic "Two people married to other people fall in love on a romantic European trip, having been put together alone due to circumstances and also the situation in each of their marriages." In Fonda's character's case she's simply not in love with her doting and rather 'doormattish' husband. In Finch's character's case his wife (Landsbury) is a miserable joy-killing shrew of a woman who is playing ever the martyr and guilt-tripping him over a past tragedy in their lives. While Fonda's husband can't make the trip, Finch and Landsbury end up fighting and she walking out, leaving he and Fonda to continue on alone.
The back story on Fonda's character is that she has been sickly since early childhood, having had multiple surgeries on her lungs and nearly dying. In any normal family of the time that would mean the only sensible course of action, that being no one smokes near her. But in THIS film the production (writers, director, producer, etc) all thought it was no big deal to just have all involved puffing away like steam engines including Jane's character herself.
While the view on smoking was a little different back in '63 than it is today it is still fairly unthinkable that a physician would raise major concern over a trip by car through the mountains due to a little rain yet have no quarrel whatsoever about a girl with serious respiratory ailments smoking like a chimney.
As for the ending all I'll say is I found it abrupt, unsurprising, and disappointing, Fonda herself is absolutely gorgeous. The vistas and views of the countryside are spectacular. The acting is decent. The story and plot is where this film falls flat.
4/10