Grand Theft Auto IV Walkthrough

Drive your vehicle around the block to the front of the building as marked down on your HUD. When you do, you'll see the mobsters walk out of their meeting and get into the car you just strapped a bomb to. Now, it's time to follow them to their destination. They'll take a long, roundabout way to get there, and we won't even tell you where they're going to end up (so you avoid the urge to skip ahead to the location, which won't work). So, just follow them, but don't get too close, and don't stray too far. Definitely lean towards the latter, though, since the game will warn you if you're too far away, at which point you can just step on the gas and catch up.

When you arrive at your destination, which is one of the mobsters' compounds, you'll see them park their car and then they all will congregate. Now seems like a great time to detonate the bomb, since Gerry made sure you knew that none of them should live. So, get out of your car and head onto the slight hill across from the compound. Once you arrive at the designated spot, break out your cell phone and call Gerry. Choose the "Detonate" option, and the bomb will explode in glorious fashion.

The bomb will cause a massive amount of damage and take many lives, but there's going to be some remaining foes that weren't killed in the blast. The game will instruct you to eliminate any remaining foes, which are represented on your HUD as red dots. So, break out an automatic weapon and run towards the compound to mow down the stragglers. There's plenty of cover for both you and your enemies to work with due to the explosion's debris, so use it wisely, and navigate around it to nullify all enemies. Then, to fully complete the mission (at which point a phone call to Gerry will occur), grab a nearby car and lose the cops.