And the cast just gets better and better.

The Hollywood Reporter is …well, reporting that Academy Award nominee Michelle Williams (Brokeback Mountain) is in final negotiations to join the cast. Leonardo DiCaprio, Mark Ruffalo and Ben Kingsley have already been announced.

Williams will play, in flashbacks, the late wife of U.S. Marshall Teddy Daniels (DiCaprio). Teddy is haunted by the memory of his wife.

He and his partner, Chuck Aule (Ruffalo), travel to Shutter Island to investigate the disappearance of a patient from the Ashecliffe Hospital for the criminally insane. Sire Ben Kingsley plays Dr. Cawley, head of said hospital.

Shooting is expected to begin in early spring of 2008.

To read our previous posts about a Shutter Island, go here.