The Black List script by Arash Amel is set in 1962 when French prime minister Charles De Gaulle gave Monaco's Prince Rainer III six months to change the country's laws that allowed it to become a tax haven. In this time of crisis, though, former Oscar-winner and mother of two Kelly managed to maneuver behind the scenes and help her husband avoid political troubles.
Roth's Rainer III is described as "ambitious and strong-headed" and "while he initially lets his emotions get in the way of his work and marriage, he eventually lets Kelly guide him in decision-making." Langella, meanwhile, is set to play Father Tucker, a priest who is responsible for setting up Rainer and Kelly and is a major advisor/therapist to the pair throughout their time together.
It's an interesting casting move Dahan has pulled here -- though we were expecting a European thesp to fill Rainer's shoes. Roth seems like a quality choice, and he still has the ability to surprise, so we'll see what he brings to the role. Lensing on "Grace Of Monaco" begins in France this fall. [Variety/Deadline]