FICTION : A RELUCTANT HERO: A NOVEL OF WORLD WAR II by Francoise Sagan; translated from the French by Christine Donougher (Dutton: $16.95; 191 pp.).

Sometimes, the difference between freshness and cliche is no more than a hair’s breadth. What, after all, is fresher--or more predictable--than youth; what experience as unique--or as common--as falling in love?

Francoise Sagan, who rocketed to fame in 1954 with her novel, “Bonjour Tristesse,” has continued to tread the fine line between triteness and truthfulness. Her latest novel, “A Reluctant Hero,” spirits us back to Vichy, France, in the summer of 1942, where the complications of a romantic triangle are played out on the stage of the vaster conflicts of war and the struggle between good and evil. The reluctant hero is Charles Sambrat, a handsome, cheerful ladies’ man who owns a leather-goods factory and lives in a comfortable country house. His childhood friend Jerome, a serious, intellectual man, and Jerome’s sensitive and captivating mistress, Alice, pay Charles a visit in the hope that Jerome may persuade him--and/or Alice will seduce him--into cooperating with their work for the Resistance. As Charles and Alice become increasingly attracted to each other--according to plan, yet far more deeply than planned--the reader knows what to expect.

Yet Sagan has invested this simple story with subtlety and insight, revealing the tang of real emotions and thoughts. By the novel’s end, we see their earthly loves in the context of a loving Earth, who continues to feed and shelter “her crazy . . . impassioned . . . foster children” all over Europe, trying to soothe their violence with the unusual beauty of the summer of 1942, as yet unaware “that her children, those transitory creatures, had discovered the means not only of dying more quickly on her flanks, but of causing her to die along with them . . . their foster mother, their only friend.” Sagan’s use of the pathetic fallacy in this paean to Earth has real pathos as well as mere sentimentality, and the same can be said of the novel as a whole.