Watch Dogs Backseat Driver (Chapter 1)
To get to this mission, find the starting point in a parking lot in The Loop. Look on your map for a purple circle, the person hacking into you is somewhere in that circle. Use your phone's profiler to quickly scan people in the park area to find out which one is the hacker.
Once your phone uncovers the baddie, chase after him and kill him.
If you were not subtle, you may need to run from the police. Shake them by driving away as fast as possible. Once you're safe, the game has you jump through a few menus to show how to access side missions.
Once that's taken care of, get back to that parking lot at the mission start. Once back, actually start the mission. Hop into a car and drive to the first marker. Make special care to avoid going into the yellow circles on your mini map. If you stay in them for too long, the cops will notice you and chase after you.
Eventually, you'll get to a back alley right along side the river. Scan the garage door back here to open it up and find the guy you need to drive around.
Once in this new car, drive away. You need to be careful though, cops are all over.
Make sure to avoid all of the helicopter search lights and any direct visual contact with officers in cars. Get to the next marker on your map. You run into two men who are not exactly friendly.
Now that the driving is done, have a call with Jordi and you'll complete the mission.