The Netflix algorithm thought I'd like this a lot better than I did. Maybe I just wasn't in the mood.
The story is that Donna (Meryl Streep in the first movie) has kicked the bucket, leaving her daughter Sophie (Amanda Seyfried) and widower (Pierce Brosnan) bereft. The movie also does an origin story, describing how Young Donna (Lily James) came to be impregnated with Sophie and wind up on that picturesque Greek isle owning a hotel. There's a lot of bouncing back and forth between past and present.
Oh, and Cher shows up, playing Donna's mom, Sophie's grandma. Also: Andy Garcia as (ta da!) "Fernando". What's he doing here? C'mon, guess. I bet you're right.
And mostly it's just an excuse for big dancing/singing production numbers with more ABBA songs. Unfortunately, they used all the really popular ABBA songs in the first movie, so the ones here are mostly second-string; I didn't even recognize some of them (but I am not really an ABBA fan).
Still it's kind of a hoot to see Pierce Brosnan, Stellan Skarsgård, and Colin Firth try to dance and sing. They look like they're having a good time. (Although whenever I see Stellan Skarsgård in a movie, it makes me want to watch The Hunt for Red October again.)