Movie sequels can be a challenge since much of the energy that makes the first film memorable has already been expended. Prequels can be even trickier, especially since so much has already been said and done in the original.

With its misleading title that might make you think it’s a sequel, “Mamma Mia! Here We Go Again” is a prequel to the events that take place in the immensely popular musical “Mamma Mia!” (2008) that had its origins in a popular stage play.

The trailer will make you think you’ll get a big dose of Meryl Streep and Cher, both of whom can carry a mean tune. You’re not. Not one of the songs is memorable, and with a complicated plot that evolves around previous action and depends on current situations, things just get chaotic.

The opening scene makes it clear that Meryl Streep’s character Donna has passed. Although she does return in a cameo at the end, this film sorely needed her energy and talent. Cher shows up in the last fifteen minutes to belt out a couple of numbers.

Donna’s daughter Sophie (Amanda Seyfried) has worked hard to fulfill her mother’s dream of renovating an old farmhouse on a beautiful Greek island and turning it into a hotel. Just when the grand opening is imminent, a terrible storm blows through and destroys the party favors.

This situation becomes subplot as the scene shifts abruptly to past action, and we see what happened many years ago with Donna’s escapades. In the first “Mamma Mia!” we learned that it’s impossible to know which one of three men is Sophie’s father since Donna’s relationships with them were all one-night stands in succession. (Don’t judge.) Through a series of events orchestrated by Sophie in the first movie, all three men are invited to the island, and Donna faces facts. All three will claim a relationship with Sophie, and they will become life-long friends because of it.

The three fathers make their way to Sophie’s grand opening. Now jump to the past to fill in the escapades of young Donna (Lily James) and her three men.

Everybody has a younger actor playing his or her youthful self. From Donna’s two best friends Rosie (Julie Walters/Alexa Davies) and Tanya (Christine Baranski/Jessica Keenan Wynn) to the three fathers Sam (Pierce Brosnan/Jeremy Irvine), Bill (Stellan Skarsgard/Josh Dylan), and Harry (Colin Firth/Hugh Skinner), much is made of their younger selves and the men and women they have become.

The only thing of interest in all this is the casting, and at times, that’s a little blurry. This is one musical that’s slightly out of tune.

Rated PG-13 for some suggestive material

Marilyn Robitaille writes film reviews for the Stephenville Empire-Tribune and Glen Rose Reporter.