William Sadler announced via Twitter more than a week ago that he was off to Vancouver to work on Fringe.The actor previously appeared as Dr. Bruce Sumner — head of St. Claire's Hospital — in the first season episode "The Equation" where he actively tried to get a visiting Walter reinstitutionalized. Walter first took residence in the mental institution following the fire in his lab that led to the death of Carla Warren, his assistant.
Dr. Sumner's rationale for keeping Walter was that he wasn't fit to be in the outside world. The return of the good doctor seems to hint that Walter will somehow find his way back (as a visitor?) to St. Claire early in the upcoming season.
With filming of the new season underway, more details are starting to emerge on the story line following Peter's timeline reset in the season three finale. Beside being largely Peter-free, it seems the first block of nine episodes will feature a very different — read even less balanced — Walter, with Olivia having replaced Peter as his caretaker or custodian. In this context, it will be interesting to see how the show and Walter handle a visit to St. Claire.
Sadler later also tweeted a picture of John Noble and himself on the set of Fringe season four.
The fourth season of Fringe will premiere on Fox on September 23.