|If this mission doesn't appear on your map, then you will likely need to do the Strangers and Freaks mission, Pulling Favors, for Tonya first.|
You can grab this mission from your house. When you gain control, follow Lamar and Chop around the corner to a white van. Get inside, wait for Lamar and then drive to the waypoint on your map. Once you get there, a scene will play out with the target driving away on a bike.
Sprint back to your van and give chase, using your ability to keep yourself close. You don't really need to catch up to him, since he will eventually crash on his own. When that happens, get out of the van and continue the chase on foot, making sure you jump over any walls or bust through some.
Once you catch up to the guy, you will be in a train yard and he will be hiding in one of the cars. Switch to Chop to let him try to pinpoint his location, then switch back to Franklin. Go up to each of the cars and open it to find they are empty. Switch back to Chop and he will run off to another dog, so go back to Franklin and try to call Chop back. However, Chop takes a liking to this dog and you must go over and pull him off yourself.
After that, there will be some more train cars for you to open, one of which houses the guy you're looking for. Chase him a little bit more until you finally catch him and stuff his butt into the back of the van. Start driving back to Lamar's place, until he uses his cell phone and you have to release the guy. Drop off Lamar at the rec center to finish the mission.