In the 1996 film "The Rock," the stolen chemical weapon is VX gas.
The film’s plot begins when Brigadier General Francis Hummel and a rogue group of Force Recon Marines steal 15 rockets from a U.S. Navy weapons facility. Each rocket is loaded with VX, an extremely lethal nerve agent, and the group uses the weapons to threaten San Francisco from Alcatraz Island.
VX is a nerve agent that disrupts the nervous system by blocking acetylcholinesterase, causing uncontrolled muscle activity, paralysis, and potentially death. The movie dramatizes its effects and delivery, so its presentation is more cinematic than scientifically precise.
A common mix-up is anthrax, another notorious biological weapon, or mustard gas, a blister agent. Neither is the weapon stolen in The Rock. The film also became associated with a real-world intelligence controversy after descriptions in a false Iraqi weapons report reportedly resembled the movie’s fictional chemical weapons.