A terrific cast can do little to save a lightweight comedy about mature women who, thanks to a shared book club reading of Fifty Shades of Gray, decide that they must fight against the dying light of their aging libidos. Those who know that Book Club stars Diane Keaton, Mary Steenburgen, Candice Bergen and Jane Fonda will have their expectations raised -- only to be crushed by an insipid premise and shallow execution by director Bill Holderman, who co-wrote the screenplay with Erin Simms. Keaton plays the recently widowed Diane, a woman who's being pestered by her daughters (Alicia Silverstone and Katie Aselton) to leave California and move in with one of them in Arizona. Fonda plays Vivian, owner of a major hotel who claims to have cherished her life of sex without emotional attachment. Bergen portrays Sharon, a respected judge whose husband (Ed Begley Jr.) left her for a younger woman. Steenburgen's Carol is married to the recently retired Bruce (Craig T. Nelson), a man who has lost all interest in sex. Crippled by a fear of flying (in planes and in her social life), Keaton's Diane meets a handsome older man (Andy Garcia) on a flight to Arizona. Fonda's Vivian finds herself being pursued by an old flame (Don Johnson), a guy whose proposal she declined many years ago. Adding to the overall mediocrity are Richard Dreyfuss (as one of Sharon's first online dating partners) and Wallace Shawn (another of Sharon's suitors). Nothing of note happens in this predictable outing, but it is marked by a certain sadness, the sadness of watching gifted actresses play desperate women in the service of a movie that has nothing in mind that doesn't spring either from cliche or from the dictates of the kind of screenwriting that makes it seem as if these characters have lived most of their lives in sitcoms.