Follow the architect.
Start walking toward the architect’s red car. As you pass the parking booth, a foreman tosses Franklin a hard hat. The architect exits his car and starts walking through the site, carrying a briefcase with his building plans. Walk a respectable distance behind him. (Listen to the amusing snatches of on-site conversation as you go.)
Follow the architect all the way to a pair of orange elevator cages. He gets in one cage and rides up. Hurry into the other cage and activate it to follow.
Get the architect to give up the briefcase.
At the top, follow the architect across the floor until you get a new onscreen prompt. Wait until you’re around the corner and the other workers can’t see you. Then rush up behind the architect and bump or punch him. You can also hold him at gunpoint. chip drops his briefcase.
Pick up the blueprints and leave the site.
Quickly snag the briefcase, then run back to the elevator cages and ride back down to ground level. The construction workers are hostile red blips on your radar now, so sprint! Guys chase you across the construction site as you run back to your car and speed away. (Make this exit from the site within 45 seconds to fulfill the mission’s lone Gold Medal requirement”)
Lose the cops, then go to the garment factory.
Your robbery also triggers a two-star Wanted Level, so you’ll have to lose the cops with standard evasion maneuvers. When you get clear, follow the yellow route back to Lester’s factory and head upstairs to the destination marker just outside the office. Franklin hands the blueprints to Lester, who pins them up on the planning board.
Watch the planning session.
Lester presents the options. The more complex choice is the “Fire Crew” approach: Hijack a fire truck and gear; use the janitor’s ID to enter the FIB building; mop your way to critical locations and plant firebombs; detonate the bombs to trigger a fire alarm; use the hijacked fire truck and dress as firemen to get unhindered access inside the building; then steal the containment drive where all of the Bureau’s high-security files get shifted in an emergency, such as a fire.
The other option, the “Roof Entry” approach, is simpler but more muscular: Make an aerial drop onto the FIB building’s roof, work your way down to a computer terminal, and hack into the system from there, on site.
Pick an approach and crew.
Choose an approach and select the crew you want. You need two gunmen for “Fire Crew.” For “Roof Entry,” you need a hacker, a gunman, and a driver. When you’re finished, a last cutscene plays: Franklin exits while Michael and Lester briefly discuss Trevor’s impact on the Union Depository gig. Finally, Michael leaves the office and the mission ends.