Concrete Jungle, unlocked by Jamaican Heat, is the first Grand Theft Auto IV mission from the Rastafarian Little Jacob. Little Jacob wants Niko to pick him up from his apartment on Dillon St in Schottler, Broker, Liberty City and take him to Saratoga Avenue in Willis for a drug deal because he is too "high" to drive. Niko also needs to back Jacob up in case the deal does not go according to plan. 

• Meet Little Jacob at his apartment on Dillon St in Schottler, Broker, Liberty City. 
• Jacob asks Niko to take him to an apartment on Saratoga Avenue in Willis for a drug deal. Jacob also needs Niko to watch the back of the apartment if things go badly, and to act as the getaway driver. 
• Get in Jacob's car.
• Drive to the block Jacob has designated for the deal.
• Jacob gets out of the car and tells you to park in the alley across the street.
• Wait there until he summons you.
• The deal does not go well: Jacob says that the alleged dealers do not have any drugs and just want to take Jacob's money and escape out the back. He tells you to take them out.
• Run over as many as you can with Jacob's car.
• Get out of the car and finish off any remaining with your pistol.
• Once the area is clear, return to the car and get Little Jacob.
• In the car, Jacob directs you to a Meadows Park townhouse. Follow the GPS to the location.
• Get out of the car and help Jacob take out the guys in the house.
• Climb the stairs.
• Take cover against the wall.
• Aim around the corner to take the guy out on the stairs with a headshot.
• Go to the window.
• Lean out to take out the guy with the shotgun.
• Proceed inside to take out the two dealers.
• Get weapons from the dealers that you have killed.
• If you need a health pack, there is one on the table inside the house.
• Once all of the dealers are dead, Jacob tells Niko to drive him back to the Homebrew Cafe.
• Successful completion earns $200, and unlocks the second Little Jacob mission, Shadow.