Lydia the hostage negotiator believes Nick, and even decides to get outside to show her support and stop SWAT swooping down. Soon enough she leaves and her partner is tricked by Nick's old partner, who locks them out and tries to talk to his old friend - but Nick doesn't trust him.
The corrupt cop -- and Smoke Monster from Lost - is told by Englander (what a surname -- talk about pointing out the obvious that all bad guys in movies are English!) to take down Nick. Sensing his opportunity now that Lydia is out the room, SWAT swoop down. Nick jumps into the arms of one of the guys, then dances around the building and leads a chase through the hotel.
The Smoke Monster has told his men that Nick has an explosive trigger, so they must shoot to kill. In the chase, Nick is handed the stolen diamond from the concierge we met before.
Nick manages to get to the roof but is soon surrounded. Lydia shows up to save him, but is escorted away.
Englander is next to show up -- with Nick's little brother and brother's girlfriend as hostages. They want an exchange for the diamond ... and Nick gives in. Englander, like all the best and most inept bad guys, leaves the scene before he can see Nick die and "will just assume everything will go according to plan" Dr.Evil style.
Meanwhile Lydia has overpowered the SWAT team member in the lift, and gets back to the roof to help them out.
Nick's old partner shows up just in time and takes a few shots at the corrupt cop, but he's wearing a vest. The cop returns fire, and Nick's partner is hurt bad. As he is dying, he apologizes to Nick - he was 'in' on the plan, but never knew that Nick would be the scapegoat. Lydia shows up just in time to take out the corrupt cop who is about to pull the trigger on them all.
Nick can only look from the roof at Englander walking towards his limo, about to get away with it all. So he takes a few deep breaths, runs along the ledge and jumps. The crowd gasp. Nick lands squarely on the large bouncy castle set up ... and then none the worse for wear it seems, bounces off, casually walks out through the crowd and few hundred cops, and grabs Englander. He beats him and then takes back the diamond.
Rather than acting all innocent and claiming it was planted, which any court would probably believe, Englander just gives up and pulls a gun. A crazy dude from the crowd rushes out to protect Nick, his new hero, and the cops arrest Englander.
A little later, Nick is released from prison and taken to a local bar by Lydia. They are served by the hotel concierge -- who is Nick's father. Nick's little brother then tells the bar to be quiet and proposes to his girlfriend (with a nice diamond ring taken from the vault before), who fights back the tears to say 'yes'.