Nothing like crashing a party at the Ambrose Theater. Head down the small alley by the WKZ van and access the junction box to unlock the side door, allowing you to take the other front door past the pedestrians.
Once inside you will find that Defalt has hacked a few of the partygoer’s phones, leaving playful messages for Aiden. Make your way through the party, accessing the profiles of the hack phones and hacking them to trace Defalt’s location.
Once you have hacked the three phones you’ll need to reach the access point via the cameras on the balconies above and solve the rather large puzzles. Don’t be overwhelmed and make sure that the timed nodes in the second puzzle are not receiving power and counting down and you’ll complete them in no time.
After hacking Defalt’s computer the guy will cause a Blackout and you’ll need to pursue him on foot. Start running east before the lights even come back on and climb up the boxes to his previous location. After taking a trap to the face, climb the ladder and gather the items as you run after Defalt, you can’t catch him so there is no point to ignore the crafting items.
On the roof Defalt’s Fixers who want to keep their boss safe. You have a few options, cause a Blackout and run for it, use environment objects to kill the enemies, or go to all out war with your fun weapons. Head down the roofs and when you reach the bottom Defalt will head off in a car.
Note: It is possible to get the Blockers off at the first intersection and stop Defalt before you lose the ability to hack the environment, but most of the time you will fail and when you do manage to do it you may bug the missions and Defalt will be stuck in his car with the "Catch" objective up.
Pick a car that you can handle and keep close to Defalt, watching his brake lights to know when to turn. You also have to watch out for him using the traps on you, such as Blockers, which will slow you down if you get too far behind. Don’t worry if you get stopped for a minute because Defalt’s driving path circles around and allows you to catch up by taking shortcuts.
Once the download is complete your objective updates and Defalt will no longer drive on a set path. On the plus side, you now have control over ctOS again and can use your hacks against him. It is possible for Defalt to escape and complete this mission…it just depends on how generous you are.