Grand Theft Auto: San Andreas Walkthrough

Rosie is going stir crazy sitting around in his hotel room, thinking he could be taken out by a Mafia bullet at any time. Instead, he's ready to take matters into his own hands. He decides to drag CJ along for the ride, without telling him where they're going.

Head to the abattoir, marked by a yellow blip on your radar. It's time to pay a visit to one of the families and make your presence known.
Once you arrive, head inside.
Watch the cutscene and see CJ cause mischief. With the warehouse in peril, it's time to make it out alive. When you take control, kill the guy running toward you with the chainsaw. Take out the remaining cronies. If you need health, a heart is sitting in the room at the tail end of the room. Head inside and grab the fire extinguisher while you're there.
Shoot through the fire to kill the guards on the other side. When it's clear, use your extinguisher to put out the fire.
Kill any remaining guards still inside.
Make your way to the next room and kill the next set of guards. If you need body armor, there's an adjacent meat locker that you can enter near the fire you extinguished.
Once you've taken out the guards in the next room, move to the next hallway. Be sure to keep an eye on Rosie's health in the top right-hand corner of the screen. If he dies, you will fail the mission.
Follow the winding path to the exit. Several guards will be waiting for you both on the ground and on top of the boxes.
Once you've exited, make your way back to the casino, marked by a yellow blip on your radar. Arrive safely and you've successfully completed it.