Robert De Niro, Diane Keaton, Katherine Heigl and Amanda Seyfried are set to star in the indie comedy "
Gently Down the Stream."
De Niro and Keaton will play a long-divorced couple who, for the sake of their adopted son's wedding and his biological mother, pretend they are still married. They quickly learn that acting the part isn't easy, especially when their past, present and future unravel for all to see.