Amber Tamblyn has signed on to star in "Blackout," an indie thriller being directed by Rigoberto Castaneda. Simon O'Leary and Valerio Morabito are producing.

The script, by Ed Dougherty and Morabito, revolves around three people who are trapped in a hospital elevator for almost 24 hours as what at first seems like an inconvenience turns into a nightmare.

Tamblyn will play a young woman who is trying to get to her grandmother in the hospital who is moments away from death.

Also cast in the film are Aidan Gillen ("The Wire") as a doctor who happens to be a psychopathic killer, and Armie Hammer, a teen who wants to run away with his girlfriend.

Shooting begins early next month in Spain.

Tamblyn next appears in "The Grudge 2," which opens Friday. She also stars in the upcoming "Stephanie Daley," opposite Tilda Swinton.

Tamblyn and Hammer are repped by Endeavor and Hyler Management. Tamblyn is additionally repped by Sloane Offer Weber & Dern. Gillen is repped by Endeavor.