In New Alcatraz, the world's most secure
prison located in
Antarctica, a drilling operation inadvertently releases a giant,
boa constrictor (fictional species
Serpuca largas) from a large, hollow rock that had been preserving it in
suspended animation. The Boa chews a hole through the
ice, enabling it to escape into the prison. The hole is discovered by workers and Jenkins, a guard is placed on it until the
engineers can assess the hole and block it up. Jenkins hears a strange hissing noise in the tunnels and is sent by Sergeant Quinn, his supervisor, to investigate; Jenkins, unnerved, requests backup, causing Quinn to send the engineers, Scott Poluso and Goodman, to help him. Jenkins is stalked and killed by the Boa; arriving on scene, Poluso and Goodman grumble about being woken up.
Blood drips down from the pipes onto Poluso, causing him to stare up in confusion, just as the Boa attacks him and Goodman. The engineers’ screams can be heard as the Boa begins to move further into the prison. The prison sends out a distress call which is received by the
United States military. They hire married
paleontologists Robert Trenton and Jessica Platt-Trenton to assist a military team led by Major Larsten in the search to destroy the Boa. When they arrive at the prison, they discover a group of survivors, led by head of security Quinn and prison warden Fred Riley. The security and military personnel split up and set out to find and kill the Boa whilst Robert, Jessica and Fred watch on in the control room. A soldier named McCarthy is killed by the Boa while his partner Simmons is found shot dead; one by one, the other personnel are also killed. Robert and Jessica join in the hunt. After a
skirmish with the Boa, a
gas pipe ruptures and explodes, killing the remaining security and military members. Robert and Jessica survive and flee from the Boa, but Jessica is seemingly killed. Robert returns to the security room and convinces Fred to release the prisoners to help them escape. Fred releases the prisoners, and the group devises a plan to escape. During the escape, one of the prisoners, a "
black hat"
hacker named Kelly Mitich, attempts to save himself, only to be killed by the Boa and accidentally causing another gas explosion, killing Fred. Meanwhile, the other group is led by Chechen prisoner Yuri Breshcov and his cousin Peter Yuvol who had been arrested for attempting to purchase mid-range
nuclear missiles for
Chechnya. Yuri finds Jessica alive, and they take her in. The Boa then kills Peter and prisoner Jose, but Yuri and Jessica escape to the surface. Meanwhile, Robert and prisoner Patricia O'Boyle, a member of the
Irish Republican Army, attempt to escape, but the Boa kills Patricia while Robert escapes to the surface. Robert, Jessica, and Yuri attempt to escape on the military plane. However, the Boa sneaks onboard and kills one of the pilots. In the ensuing battle, the Boa is ejected from the plane, but Yuri is dragged out with it, and the two fall to their deaths. Robert and Jessica, bewildered but alive, fly to safety. ==Cast==