“The Long Weekend” is the new thriller from British author Gilly Macmillan. “Three Couples. Two Bodies. One Secret.” reads its cover.
Any summary of Macmillan’s book is going to suggest it’s stuffed with clichés. Macmillan seems, for example, to have appropriated her plot from “A Letter to Three Wives,” the Oscar-winning 1949 film written and directed by Joseph Mankiewicz in which three friends receive a letter from a mutual acquaintance telling them that she has run off with one of their husbands.