Mission 2- This Changes Everything
When the cutscene stops, follow your objective point into the Reserve building. After enduring a certain amount of verbal abuse, pick up the bags of money from the back of the truck.
Follow the guard down some stairs and past the gold reserve to the burn room. Once your partner and the guard start chatting over the sweet smell of burning money, step behind the guard and take him out with the [Q] key. This is the first time in the game that you'll be required to attack someone, but it won't be the last.
You’ll now get a very soft intro to stealth, using [X] to enter ‘stalking mode,’ and [CTRL-LEFT] to enter cover. Taking out the two guards in the next room should be easy, as long as the talkative guard isn’t looking directly at you when you choke out his partner. You can also arm yourself with the guard’s gun, but keep an eye on the ammo- you're about to use a lot of it.
There's a safe-cracking cutscene in which Things Go Wrong, and now it's time to let your bullets do the talking. Your objective here is to defend Giorgi, but he's not terrible at defending himself, so don't be afraid to move around the battlefield.
Immediately on exiting the vault you'll run into two guards- make your life easier by shooting them while they're still at the top of the stairs, before they take cover. Other guards will rush the room from the north, west, and south. The quickest way to take them out is to stay in the intersection and shoot them before they find cover. If you keep getting shot in the back, try hanging closer to Giorgi and taking pot shots as they advance.
Either way, once they're dealt with it's time to crack open the armory for some real firepower. You'll be treated here to a brief tutorial on the crowbar process. Follow the two-step sequence to pry open the door, then grab the machine gun & pistol and re-join the fray. Now it's time for serious mayhem and- no wait, cutscene. And the start of the next chapter.