Museum Piece

"Gorgeous, huh? Like condensed money."

- Isaac Roth, about the Diamonds.

Museum Piece is a mission given to Niko Bellic by Ray Boccino in Grand Theft Auto IV. In this mission, Ray wants Niko to sell the load of diamonds they obtained in the earlier mission to a buyer at a deal in a museum. Johnny Klebitz will be there as well with Niko to provide support and take his cut of $1 million back to The Lost Brotherhood. However, the deal goes horribly wrong upon an interruption.

Description
Ray meets Niko at Drusilla's and they talk in the kitchen after Ray hangs up his phone. Ray yells at Niko for not calling him sooner since he needs him to sell the diamonds. Niko tells Ray that he will only do it if he promises to find Florian Cravic for him, to which Ray reluctantly agrees. He then sends Niko to the The Libertonian museum in midtown Algonquin to meet up with Johnny Klebitz, a member of The Lost Brotherhood who had already participated in another deal with Niko, so they can sell the diamonds to the Jewish Mob representatives, Isaac Roth and Mori Green. During the deal, Luis Fernando Lopez ambushes the trade and kills Mori. Isaac takes the diamonds while Johnny snatches the money, Luis takes backs the diamonds from Isaac, and Niko is forced to shoot his way through Isaac's henchmen to exit the museum empty-handed. After getting out, killing Isaac's men that were lying in wait outside and escaping police pursuers, Niko calls Ray and informs him of the what went on in the museum. A furious Ray tells Niko to meet him later so they can deal with Johnny.

Mission objectives
In order to complete the mission the player must:
 * Meet Johnny at the side entrance to the Libertonian
 * Escape the Libertonian
 * Lose Isaac's crew

Enemies

 * Jewish Mob
 * Ancelotti Family

Walkthrough

 * An SMG would be useful in this situation as it can quickly neutralize some of the goons. Thus, it is revealed that Niko uses one during the mission from both Johnny and Luis' point of view.
 * A good strategy is to use Dwayne's special ability and get 2 of his goons to back you up.
 * Also if you are planning to drive to the museum, it is also a good idea to leave the car door open and leave the engine running.

After the initial cutscene, head over to the Libertonian museum in Middle Park, Algonquin. Meet Johnny Klebitz at the side entrance to the Libertonian. They meet the buyer, Isaac Roth with his men inside. A cutscene shows the diamond deal ambushed by Luis Fernando Lopez. Johnny takes the money and flees, and Luis steals the diamonds from Isaac, while Niko has to shoot his way out of the museum.

Remain in cover and take out any Mafia or Jewish Mob members. Move forward down the lane and regain cover when Niko begins to lose health (or armor). Return fire to everyone that is in sight. Once the player is at the end of the lane, turn left and left again to go down the stairs. Shoot the enemies coming up the stairs and get in cover near the bottom of the stairs. Make sure to get the armor pickup once Niko gets to the bottom of the stairs. It's hard to miss, but go left at the bottom of the stairs and find the armor in a small, low booth.

Kill the rest of the Mafia and Jewish mobsters (take your time) and go out of the door (South of the North Entrance). Follow the path until you get out of the museum. Eliminate anyone in the way. Once Niko gets outside, shoot down the drivers of the cars parked outside and lose your wanted level. Isaac's Crew will give chase in their cars, attempting to kill you, once you have lost them you will call Ray and explain what happened. (The achievement/trophy Impossible Trinity is gained on completion)

Deaths

 * Mori Green - Killed by Luis in order to retrieve the diamonds.
 * Isaac's crew - Killed by Niko in order to escape.
 * Johnny Klebitz (optional) - Can be killed by Niko, although it does not affect the story.

Trivia

 * This mission is seen again as Collector's Item in The Lost and Damned, this time from Johnny's point of view and again as Not So Fast in The Ballad of Gay Tony, this time from Luis' point of view.
 * Johnny is seen running out of the museum with no weapons.
 * Johnny Klebitz can be killed by Niko after he reaches the North exit, although it doesn't effect the story. the mission'll fail only if Johnny's killed before he reaches his exit
 * There is no ladder where Isaac hides; in TBoGT Luis escapes to the roof by climbing a ladder
 * The Desert Eagle is first introduced without cheating (unless you killed Playboy X and took his in The Holland Play, which may or may not have been played before, or if you acquired one from a weapon pickup throughout the city), many Jewish Mobsters apparently hold them. This is because the Desert Eagle is an Israeli weapon.
 * If the player wanders back to where the deal took place (during the mission) they can find Isaac Roth hiding behind some crates bad-mouthing Ray Boccino, and mourning the loss of Mori Green, though in Not So Fast, Luis Lopez knocks out Isaac and takes the diamonds right from his hand.
 * If Isaac is killed, the mission will fail (text displayed will say "Isaac is dead.").
 * Before descending to the bottom floor, the player can shoot at the hanging dinosaur bones, if done properly, the bones will fall onto unsuspecting mobsters below.
 * After successful completion of this mission, the Xbox 360 Achievement/PS3 Trophy Impossible Trinity is unlocked. In The Ballad of Gay Tony, completing the mission will unlock the Diamonds Forever achievement.
 * The achievement Impossible Trinity refers to the three protagonists of the GTA IV Era coming together in one place at the same time.
 * During this mission and Collector's Item, Luis is not seen during gameplay. He would not be seen anyway as he snatches the diamonds and escapes upwards, before Niko and Johnny are out.
 * Outside the North entrance, a Hellfury can be seen, as Johnny's getaway vehicle. This is because the Hexer had not been included in the final version of GTA IV.
 * If you are quick enough and follow Johnny out his exit, he becomes a random pedestrian and walks around instead of escaping. It is possible to kill Johnny without failing the mission when this happens.
 * Even if you kill Johnny, Niko will still mention him during the phone call with Ray after the mission is completed.
 * If you go back to where the deal took place, you will see three corpses, however, instead of Mori Green, there will just be an old fat Jewish man in his place. This model can also be seen as a random pedestrian around Liberty City.
 * After escaping the museum, the instructions state to "Lose Isaac's Crew", although if you kill the pursuers and look at their bodies, they are actually Ancelotti goons.
 * Most of the mobsters are replaced with policemen in The Ballad of Gay Tony, which leads to a continuity error.
 * This mission, Collector's Item, and Not So Fast are the only missions where all three protagonists appear at once in the entire GTA IV Era.
 * The mission can be completed by taking the subway. If the player runs on a straight line after exiting the Libertonian (having killed the thugs guarding the exit), he will find the subway entrance to the Middle Park Station. Isaac's crew will only follow Niko down there if he takes too long to catch a train (which most likely will come just as he arrives at the platform). Since the subway follows its own path instead of that of the streets above, it can be seen as a shortcut, and the mission will be completed before the train arrives at the next station.
 * This is the last time Niko and Johnny have crossed paths.
 * This is the second time Niko and Luis have crossed paths.
 * Before you talk to Johnny when walking around him he will always look at you except when you're behind him.
 * If you walk to where Luis Lopez escapes, the window is open, and he may say something about Mori. He cannot be seen though.

Gallery
Museum Piece Museum Piece Museum Piece