The Mafia rules the street and you can't do any transactions if you aren't going to pay them. Well, at least, that is what they want, but then again, some guys are that tough that they won't back out from any fight, no matter how dangerous it is. This is true since you don't like paying those mafia. A local company wants to deliver something important and they have hired you to protect it against those mafia bandits. You know what you are getting yourself into when you accepted the job, but still, you just can't say no since the guy, who hired you is an old friend.
The idea here is to protect the truck from the mafias. You need to shoot them down before they can even get closer to the truck. You would earn money from destroying the Mafia's vehicle. You can either use it to buy better gun, hired bodyguards, or repair the damage that the mafia has done to your truck. Sure, this is a top game and it won't get any easy as you make some progress, but the idea here is to keep upgrading your gun and buying anything necessary to stop those bandits.