What can you do to improve upon an Abba musical judging by our review? Just add some Cher! Trust the Irish actor Pierce Brosnan to also save the day with a bit of singing. 

"Mamma Mia: Here We Go Again," the sequel to the first blockbuster musical movie based on Abba's classic songs really shouldn't work, and for the first twenty minutes of the sequel this week I'm afraid it really doesn't. In fact, I started to worry that it was going to be a turkey of Thanksgiving proportions.

The reason for this is that the formulaic plotlines are even sillier, this time involving the supernaturally pretty Amanda Seyfried as Sophie, the daughter of Donna (played in the first film by Meryl Streep).

Donna has passed away we learn and Sophie has taken up her legacy by opening a hotel on the same Greek island that her mother loved and had made her home.

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 Alexa Davies, Lily James and Jessica Keenan Wynn

Alexa Davies, Lily James and Jessica Keenan Wynn

In a flashback sequence, we return to Donna's graduation day in the 1970's for the film's big opening number, the lesser known but very tuneful Abba track "When I Kissed The Teacher."

Lily James takes up the story now playing Donna's much younger self and her strong singing voice carries the scene, but then the breathless choreography and the jump cut direction try so hard to divert you that you end up just hoping the sequence will end, which gives the new film a rather ominous opening.

Things don't improve at all when it's Amanda Seyfried's turn on the microphone. I have to be honest here, her voice is thinner than the atmosphere on Mars. Singing "One Of Us," another minor but enjoyable Abba track, she's flatter than the plains of Nebraska, and that's another big strike against the film.

Then into young Donna's life comes young Harry (played by Hugh Bright). Harry is the sort of Englishman who apologizes to the potted plants he accidentally brushes up against.

Bright is clearly trying to channel the younger Colin Firth (because they're playing the same guys decades apart) but he's so painfully, awkwardly English that you squirm in your seat every time he appears.

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Amanda Seyfried, Dominic Cooper and Cher

Amanda Seyfried, Dominic Cooper and Cher

It gets even worse when he has to woo young Donna in Paris because he has to sing Abba's breakthrough track "Waterloo" and he's just not up to it. First of all, to sing it you have to understand the joy in it, and Bright just doesn't. Maybe it's his screen direction, maybe it's all the clunky dialogue, but he looks embarrassed not just to be English but also to be appearing in this film.

What's the point of a big dumb Abba musical if you can't find the fun in it? Why even try out for this escapist fare if you look like you're above it in every scene you appear? The problem isn't just Bright's. All the young romantic leads in this film are Ken Dolls, him-bots obviously brought in to amp up the sex appeal but to add little to the story.

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Josh Dylan, Jeremy Irvine and Hugh Skinner are rounded out by the musically challenged Dominic Cooper as the lost boys who just don't get it. Casting these humorless lads threatens to sink the film more than once, but thankfully they're quickly overshadowed by their more mature and frankly funnier and more charismatic older versions led by Pierce Brosnan, Colin Firth and Stellan Skarsgard.

It isn't until Lily James burns the house down with her performance of "I Have A Dream" that the film finally finds its groove. She's a charmer let down by her uninspired leading men, but when she's given screen time on her own or with her two best girlfriends the film comes to life.

Julie Walters, Pierce Brosnan, Amanda Seyfried and Christine Baranski

Julie Walters, Pierce Brosnan, Amanda Seyfried and Christine Baranski

Donna is deeply missed by her daughter Sophie and by Sam (Pierce Brosnan), the man she finally married in the first film, and this development finally gives a male lead something to do other than simply be gorgeous.

Depend on the Irish to find the emotional depth in even the smallest sequence. Brosnan sings what is, for my money, the greatest Abba song that was ever written, "SOS," and he does it with minimal accompaniment, using just his own voice to completely nail the track. “The love you gave me, nothing else can save me,” he sings, and he means it.

There has always been a Scandinavian melancholy underlining these famous pop tunes, it's one of the things that makes the celebrated band so unique. They explore some of the hardest lessons of life in songs that nevertheless bring you straight to the dance floor. Only a country that is dark for half the year could have brought that kind of sensibility to the top 10.

Without giving too much away I will tell you that Cher plays Sophie's grandmother in this go around and her appearance is worth every cent of your movie ticket. I'm deadly serious. Cher singing Abba is not a gift I thought I needed until she picked the perfect track and kicked the film into high gear. The audience spontaneously applauded at my screening.

So "Mamma Mia: Here We Go Again" turns out to be better, looser and oddly more moving than the original film, thanks to very unpredictable elements like the strength of the female cast and Cher's truly barnstorming delivery. She goes head to head and icon to icon with the only band that can really give her catalog a run for its money and the result is, I'm not exaggerating, glorious.

There are even bigger surprises, like the unexpected re-appearance of a certain save the best till last Miss Streep. Look, she attended the film's opening night so the cat is pretty much out of the bag. Suffice to say that when she appears its right on time and she's note-perfect (great actors are often great singers too).

Julie Walters is dependably brilliant as Rosie, one of the original three desperadoes, backed up by the delightful Christine Baranski (a woman who has gay icon literally stamped on her forehead). But watching her onscreen I was reminded of a remark she made recently that working-class actors like she once was can no longer afford the steep tuition for acting school.

Perhaps that's why the pampered young men in the current cast all look and sound exactly alike, robbing the film of interesting younger male leads and letting down the young actresses too often.

If I have one criticism it's that "Mamma Mia: Here We Go Again" plays it a little too straight, a little too long, given the band and its very long legacy of camp.

Because of that the film doesn't quite take off until the "too cool for school" young lads finally clear the stage and let the "up for it" girls and the music do what it promises, having the time of your life.

Are you heading to see "Mamma Mia: Here We Go Again?" Do you think Brosnan does a good job? Let us know in the comments section, below. 

Pierce Brosnan attends the 'Mamma Mia! Here We Go Again' world premiere at the Eventim Apollo, Hammersmith on July 16, 2018 in London, England. Stuart C. Wilson/Getty Images for Universal Pictures