When a series of tremors rocks Los Angeles, seismologist Kimberly Stevenson is sent to investigate the quake's epicenter, a desolate wilderness known as the Angeles National Forest. Two hundred miles from civilization, Kimberly and her son, Justin, set up a research facility in an isolated mountain cabin. The project takes a sinister turn when Kimberly discovers that she has stumbled upon a test site for black market nuclear weapons. With the help of mercenary Michael Brandeis, Kimberly must race against time to stop a final underground test that could trigger the most powerful quake California has ever known.