Under Siege 2: Dark Territory is a 1995 action film, and is the sequel to Under Siege.

As in the film that preceded it, Steven Seagal plays Casey Ryback, an ex-Navy SEAL.

Casey Ryback (Steven Seagal) has now retired from the Navy, and is now a chef at the Mile High Cafe in Denver, Colorado.

Casey is taking his niece Sarah Ryback (Katherine Heigl) on a trip to Los Angeles to visit the grave of Casey's brother, who was Sarah's father. They board a train traveling through the Rocky Mountains from Denver to Los Angeles.

Travis Dane (Eric Bogosian) takes the train hostage, and starts using the train as a control center in his efforts to take control of Grazer One, a top-secret government super-weapon that is controlled by a satellite. Dane built Grazer One, but he was fired by the government before Grazer One was deployed.

Dane has since hooked up with Middle Eastern terrorists who have offered him $1,000,000,000 to use the satellite to blow up the Eastern seaboard by targeting a nuclear reactor that is under the Pentagon.

Dane uses Grazer One to blow up a Chinese chemical plant in order to tell the Pentagon that he's got control of the weapon. And at the request of one investor, Dane blows up an airliner carrying the investor's ex-wife.

A big problem is that officials can't stop Dane because they can't locate his headquarters. As long as the train keeps moving, his location can't be fixed.

Casey enlists a porter named Bobby Zachs (Morris Chestnut) to help him go after Dane. After Casey kills Dane's henchmen, and the train crashes, Casey and Dane get in a fight on a helicopter above the train. Casey knocks Dane out of the helicopter, and Dane falls to his death.