Mamie Gummer, Lyndsy Fonseca, Jared Harris

By JUSTIN KROLL

Mamie Gummer, Lyndsy Fonseca and Jared Harris have signed on to join Amber Heard and Danielle Panabaker in John Carpenter's "The Ward."

Filming is under way on the psychological thriller, in which a young woman -- played by Heard -- wakes up in a mental institution with no memory of who she is or why she is there and finds herself terrorized by a ghost.

Carpenter is directing "The Ward," written by Michael Rasmussen and Shawn Rasmussen.