John McClane takes on Hans Gruber, who holds people hostage in Nakatomi Plaza in order to steal bearer bonds. 

At this moment, we discover Gruber’s plan: Blow-up the roof of the building, killing the hostages and the FBI agents sent to help, getting away with hundreds of millions of dollars in theft.

IF McClane fails to stop Gruber, everyone in the building will die, including him. IF McClane dies, he loses the opportunity to truly make amends with his wife.