return of the detonators. McClane refuses to return them, causing Gruber to execute Ellis. While checking the explosives attached to the roof, Gruber is confronted by McClane. Gruber passes himself off as an escaped hostage and is given a gun by McClane. Gruber attempts to shoot McClane but finds that the gun is unloaded. Before McClane can act, Karl, Franco, and Fritz arrive. McClane kills Fritz and Franco, but is forced to flee, leaving the detonators behind. FBI agents arrive and take command of the police situation outside, ordering the building's power be shut off. The power loss disables the vault's final lock as Gruber had anticipated. Gruber demands that a helicopter arrive on the roof for transport—his intention is to detonate the explosives on the roof to kill the hostages and to fake the deaths of his men and himself. Karl, who is Tony's brother, finds McClane and the two fight, with Karl seeking to avenge Tony's death. Meanwhile Gruber views a news report by Richard Thornburg that features McClane's children, causing Gruber to realize that McClane is Holly's husband. The terrorists order the hostages to the roof, but Gruber takes Holly with him to use against McClane. McClane seemingly kills Karl and heads to the roof. He kills Uli and sends the hostages back downstairs before the explosives detonate, destroying the roof and the FBI helicopter. Theo goes to the parking garage to retrieve their getaway vehicle but is knocked unconscious by Argyle who had been trapped in