Mission 123 - Confront Bobby Bastian
Talk to Bear one last time before heading out. There's a pawn shop nearby with a tacvest and a diner with a medkit, if you're a little light.
This is nice little level, and it's refreshing to have a boss confrontation be on new ground.
Go around the back- there's not a door, exactly, but there's a little gap where you can vault a box inside.
Clear the building floor by floor. Wipe out the ground floor with stealth kills and silent shots, being aware of snipers on the upper balconies. There are two staircases up, but enemies greatly prefer the central one- if your killing is spotted, set your sights on that staircase and pick off the guards as they emerge.
When the ground floor is clear, ascend using the northwest staircase.
Grab a tacvest here and then clear out the atrium snipers, using the balcony as cover. Then head to the south lab. A lot of different routes pass through here, and you'll be able to drop a ton of hostiles just by being patient and alert. There's also some cash and a medkit here.
When the coast is clear, head to Bastian's office. Gun down any remaining guards, or blow them up with the barrels, and give Bobby the sharp, hard sell to acquire this racket.
Collectible alert: Vargas painting in Bobby's office