Not missable
Chapter 12: Sea Gift
Dope Deal
Henry has a plan to make it rich quick: Buy drugs cheap from the Chinese and sell it for profit. In order to start this deal, you'll first need some money of your own.
Jump into your car and take the first waypoint to the loan shark. He'll lend you nearly $30,000 dollars, but will expect a large return later. Travel to the next way point to do business with the Tongs, a powerful Chinese gang.
The Sting
The deal goes fine, however you'll be ambushed by police on your way out. Somehow Henry sees that they are fake cops and you'll make a break for it.
Before battling, there are a few collectables around, so stop to pick them up. Let Joe and Henry take point, as they can both survive multiple hits that would otherwise destroy you. There is little cover in the upper sections, so you'll need to dash along the catwalk and descend the stairs.
Outside, more reinforcements will arrive. Stay in cover and let your allies pick off the ones close by, while you concentrate on the further targets. Once the "police" are done in, steal a car and make your way to the delivery waypoint.
Head to the drop point to start your drug dealing career, which will conclude the chapter.
Source:
http://www.gamespot.com/features/6274410/p-13.html