This mission begins at Franklin's house (his old one) and available to Franklin. After some choice dialog with Trevor, get into a vehicle and take out your phone. Lester gives you a new app that will help track down Michael's location, who is being held hostage by the Chinese.
On the app, Michael's location will be indicated by a red blip and as you drive around, it will get closer (or farther). Needless to say, just follow it, turning left if it's to your left and try to get it to appear in the up direction, as you can just head straight. When you get to the location, which is a warehouse area, you'll see some Chinese guys talking out front. Note that there is a timer that appears on the way, which will disappear once you get to the warehouse.
Start by taking out those guys, which should alert the rest of them. Fight your way through the warehouse, making sure you use cover as to not get killed quickly. Watch your radar for red dots and don't leave yourself open to attacks. When you finally get to Michael, you'll gain control of him hanging upside down, and will need to kill incoming Chinese, who will come from straight ahead and to the left.
If you feel overwhelmed, don't forget to use Michael's ability. You'll switch back to Franklin, who will need to clear the corridor ahead, but will get ambushed by one guy with a knife. As Michael, shoot this guy in the head to kill him and then you'll free yourself. Now, you can freely switch between both Franklin and Michael and will need to escape.
Of course, the Chinese won't allow you to escape so easily. There will be a few in the first room and then one will use a slab of meat as cover in the next hallway. Clear out the rest and then head to the car. Normally, as you're escaping, the Chinese will give chase, but get out of the car as soon as you enter to kill two Chinese guys, who will be it. Drive back to Michael's house to finish the mission.