Walk into the yellow marker to enter the abattoir. A cutscene begins, and Carl doesn't want to go any further for the obvious fact that Johnny will recognize him as the guy who put him in this poor condition (Carl did this in the mission Fender Ketchup). Rosenberg insists that Carl come along. Johnny comes out of his office in a wheelchair and greets Ken, but as soon as he sees Carl, he clutches his heart and falls to the ground. The Sindacco's launch a full attack. One mobster throws a molotov cocktail, which creates a fiery barrier between two areas of the abattoir. Another mobster carrying a chainsaw walks towards CJ.
Kill the mobster, and any other attackers while Ken looks for a fire extinguisher. Rosie's health bar appears on-screen. Protect him and kill all of the witnesses in the abattoir. The mobsters are shown on the radar as red blips and these blips point in the direction that the mobster is facing.
Rosie will run into the freezer after extinguishing the fire. If the mobsters are close enough to the freezer, one of them will try to run toward the switch to close the freezer door, locking Rosie in, including you if you entered it. You can reopen the door if you are outside it. If you are locked inside you will fail the mission.
There are various health and armor icons scattered across the abattoir. There's a health icon back in Sindacco's office, so get it if you need it. Go through the stock house to find the exit, and again, watch out for any attackers. A few mobsters are standing on top of the boxes, and will shoot from above. Walk into the yellow marker to leave the abattoir, and get Rosie back to Caligula's. Mission is then passed.