The sunlit terrace overlooks a calm sea. But the serene Eastern European setting contrasts with the turbulent emotional squall awaiting the principal characters in the vexed new morality play at the Manhattan Theater Club. For it turns out that ''Summer,'' by British playwright Edward Bond, is dealing with the long-term personal effects of class hatred, war, revolution, and reprisal.
The principals in the belated confrontation are the visiting Xenia (Frances Sternhagen), daughter of once powerful local landlords, and Marthe (Betty Miller), her former servant now running the expropriated family villa as a guest house. Although Xenia moved to England after her father's imprisonment for collaborating with the Nazi occupiers in World War II, the postwar Communist dictatorship appears to have relented sufficiently to condone her holiday visits. In the course of these vacations, her daughter, Ann (Caitlin Clarke), has begun a summertime affair with Marthe's son, David (David Pierce), a doctor at the town clinic.
In Mr. Bond's writing and the performance staged by Douglas Hughes, Xenia is more silly and tiresome than pathetic. Furthermore, the strong, self-possessed presence of Miss Miller's fatally ill Marthe subserves Mr. Bond's thesis that the act of intervention by which Xenia saved Marthe's life did not in any way atone for the crimes of an oppressive class system. The author recalls the war itself in the person of a naively oafish German tourist (Tom Brennan) revisiting the very island on which he served as a soldier, where Nazi victims were interned and massacred. Here as elsewhere, Mr. Bond displays his facility for sharp observation and for piling up horrendous detail.
Marthe's peaceful passing after bitterly denouncing Xenia leads ''Summer'' to a sentimental quasi-resolution involving the two young people. It is another of Mr. Bond's attempts to present the effects of ideological and other conflicts in human terms. Yet notwithstanding its sympathies and commitment, ''Summer'' seems afflicted by its own self-serving doctrinaire viewpoint. As entertainment, the seaside interlude can be stirring and at times amusing. Its philosophical and ethical thrust, however, tends to be murky.
Miss Miller and Miss Sternhagen are well and ably matched as the privileged dilettante and the resolute former servant who once testified against her. Mr. Brennan enlivens the second act in a comically horrifying way. The young people are less believable, perhaps in part because Mr. Bond has left them at loose ends. The production is picturesquely served by Tony Straiges's Adriatic-like settings, sun-drenched by lighting designer Pat Collins. The Linda Fisher costumes range from Xenia's Mayfair wardrobe to Marthe's somber peasant garb.