Downton Abbey: The Grand Finale Teases Scandal for Michelle Dockery’s Lady Mary in Dazzling Full Trailer

Tensions are running high in Downton Abbey: The Grand Finale.

In the newly released full trailer for the upcoming third film installment in the hit franchise, the story kicks off with a dazzling light display as viewers are ushered into the 1930s.

Lady Mary Talbot (Michelle Dockery) is soon seen embroiled in scandal as she is revealed to have gotten a divorce from Henry Talbot (Matthew Goode), leading to her being ousted from a societal event. Her status as a divorcée even led some to question whether Lady Mary is fit to run Downton Abbey in the future.

The trailer also sees the long-awaited return of Paul Giamatti’s Emmy-nominated role of Harold Levinson, who emerges from a car to embrace his sister Cora Crawley (Elizabeth McGovern) seemingly after some extended time apart.

“The news is bad, isn’t it?” Cora asks Harold, who quips back, “How could you tell?”

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer​​, from celebrity news to compelling human-interest stories.

Downton Abbey: The Grand Finale “follows the Crawley family and their staff as they enter the 1930s,” reads a synopsis, adding, “When Mary finds herself at the center of a public scandal and the family faces financial trouble, the entire household grapples with the threat of social disgrace.”

“The Crawleys must embrace change as the staff prepares for a new chapter with the next generation leading Downton Abbey into the future,” it adds.

The film is directed by Simon Curtis, from a screenplay by Academy Award winner (and Downton creator) Julian Fellowes.

Aside from Dockery, 43, Giamatti, 58, and McGovern, 63, the extensive cast includes Simon Russell Beale, Hugh Bonneville, Laura Carmichael, Jim Carter, Raquel Cassidy, Brendan Coyle, Kevin Doyle, Michael Fox, Joanne Froggatt, Harry Hadden-Paton, Robert James-Collier, Allen Leech, Phyllis Logan, Sophie McShera, Lesley Nicol, Alessandro Nivola, Dominic West, Penelope Wilton, Arty Froushan, Joely Richardson, Paul Copley and Douglas Reith.

While speaking to PEOPLE about joining Black Mirror season 7 in April, Giamatti opened up about reprising his role — especially in the wake of late star Maggie Smith’s death last September.

“It was not the same without her, but it felt very much like in her honor in some way. She certainly still feels present through the whole thing,” Giamatti said. “Not having her there is obviously a huge loss, but everybody was still acting in her spirit.”

The PEOPLE App is now available in the Apple App Store! Download it now for the most binge-worthy celeb content, exclusive video clips, astrology updates and more!

Added the two-time Oscar nominee, “Working with her the first time around was one of the best things ever and I didn’t even really get to do that much with her.” 

Downton Abbey: The Grand Finale in in theaters Sept. 12.