The prologue starts at the restaurant, with John Lennox speaking with a former collegue. It doesn't take long before combat starts. During the prologue, you may either attack the enemies, or run past them. Since health and items do not transfer to the next mission, and because enemies respawn if you delay, it's best to simply run past them and not worry about ammo.
Restaurant[edit]
There is one thing to do, and that is to reach the elevator. There is no obstacles, beyond the enemies that drop from the ceiling.
First, run forward, and take a right to the first door.
In the second room, head to the door at the far right end of the room, and turn left to the corridor. The corridor does a left turn, followed by a right. The corridor ends at a set of doors leading to a darker gray corridor. The elevator is at the end of the tunnel.
Running without stopping is the best option, but if you choose to fight, you should search the bodies to collect their ammo. If you do run out of ammo, you can still attack enemies by approaching them and using a melee attack.
Garage[edit]
The elevator leads to the garage. Exit, and approach the car to complete the prologue, and meet with Lucius Black.