What a waste of some perfectly wonderful legends.

It’s so great to see Jane Fonda, Diane Keaton, Mary Steenburgen and Candice Bergen in a movie in 2018 — a time when most of the best roles for older actresses are to be found on TV, whether it’s the networks or HBO or Showtime or Netflix et al.

Too bad they’re floundering about in the undercooked, silly and often downright inexplicable “Book Club,” an upper-class romantic comedy that plays like lesser Nora Ephron.

Much lesser Nora Ephron.

Fonda plays Vivian, the stylish and decidedly single owner of an upscale hotel. Vivian has never wanted for companionship, but she has always put business first and never got involved in a serious relationship.

Bergen is Sharon, a federal judge who is still smarting over her jerky husband Tom (Ed Begley Jr.) leaving her a decade and a half ago. Sharon’s ex has recently become engaged to a much, much younger woman. Sharon, meanwhile, hasn’t had so much as a date in 14 years.

Steenburgen is Carol, a successful chef happily married to Craig T. Nelson’s Bruce. But ever since Bruce retired, let’s just say it’s been quite the romantic dry spell.

Diane Keaton is Diane (I guess they ran out of character names), a widow whose two grown children (Alicia Silverstone and Katie Aselton) treat her as if she’s a doddering, forgetful, ancient relic who can’t be trusted to live on her own any more — even though it’s perfectly clear Diane is vibrant, healthy and in complete command of her faculties.

Each month, the ladies get together to discuss a work of literature they’ve all just read. One month, instead of literature they decide to go with “Fifty Shades of Grey,” and while you might well expect at least one of these intelligent, sophisticated women to hurl the book across the room after 50 pages and exclaim, “I can’t take any more of this claptrap,” they’re all deeply titillated and also quite motivated by the story of the winsome young writer Anastasia Steele and the creepy and controlling billionaire Christian Grey.

Judge Sharon goes on a dating website and meets a nice guy named George (Richard Dreyfuss). Carol goes to extreme lengths to get hubby Bruce to rev up his engine. Diane falls for a handsome pilot (Andy Garcia) who made millions on an investment and lives on a magnificent spread that would have Oprah green with envy.

Even the anti-romantic Vivian allows herself to explore genuine feelings for Arthur, a former lover who has re-entered her life.

(Programming note: Don Johnson plays Arthur. It’s always a little alarming when a movie references real-life pop culture, and then something or someone in the movie further reminds us of the real world. Don Johnson is the father of Dakota Johnson — who played Anastasia in the “Fifty Shades” movies.)

“Book Club” is filmed in bright tones, and it features a bouncy score reinforcing the overall feeling of light escapism. Although some of these characters have experienced tragedies and setbacks — after all, Diane did lose her husband, and Sharon never really got over her divorce — none of them has a financial care in the world, or the slightest hint of a health concern. Life is good, and most of the “drama” they experience is self-inflicted and almost silly.

So many of the plot threads seem forced. When Diane spends the night with the pilot and doesn’t report her whereabouts to her daughters, they react as she has wandered into the desert and the police should be out looking for her. When Sharon attends an engagement party for her son, we’re reminded she HAS a son, because who knows where he’s been for the whole movie until this late moment.

We even get one of those scenes where someone feels the need to rush to the airport to stop someone else from getting on a plane.

Enough with the rushing to the airport to stop someone from getting on a plane. You can text or call that person before they board.

Heck, you might even be able to reach them in mid-flight.

★★

Paramount Pictures presents a film directed by Bill Holderman and written by Holderman and Erin Simms. Rated PG-13 (fo rsex-related material throughout, and for language). Running time: 104 minutes. Opens Friday at local theaters.