Cromwell is set to play Meryl's husband in the film. Streep evidently portrays a woman (and with Cromwell probably a couple) who loses her savings due to the shady business practices of the law firm Mossack Fonseca. Riley Keough has been cast as their daughter.
The article from Playlist also reported that there are going to be multiple A-list cameos. Meryl's role has frequently been called the "emotional through-line" of the film, but I have a feeling she might end up being a rather small roll, but hopefully not so small that it's considered a cameo.
Filming gets underway this week.