Botched
(2007)

After the heist goes wrong, Ritchie (Stephen Dorff), Peter, and Yuri are forced to take hostages from the elevator. After being forced onto the 13th floor, a strange figure starts killing them off one by one.

It is revealed that one of the female hostages Sonya is the twin of Alex, the killer. She and her brother are insane and believe themselves to be descendants of Ivan the Terrible. They kill Yuri, Peter, Dmitri, and several others. Ritchie sets Alex on fire while Anna (Jamie Murray) stabs Sonya in the neck killing her. They get away with the cross Ritchie was sent to steal.

The other lone survivor Boris, faces the dying Alex, but the floor collaspes, taking them and several bodies with them to the floor below. Security sees it and it is implied that Boris will be blamed for the killings.

Ritchie meets up with his boss, Gronzyi (Sean Pertwee) and delivers the cross. It is here we learn that the killers were the Gronzyi's siblings and the stealing of the cross was personal since he was tormented by them growing up. Ritchie is given a stack of cash for his trouble (and his family debt is paid off) and plans to head off with Anna to L.A. for a well deserved vacation.

Thanks Spectre!