With only your Silverballer and M4 (in case things go wrong), go through the door as soon as you start the mission and move left. Talk to the guard and get the real WWI pistol, then go into the bathroom and wait for a worker in green to walk in. When he uses the bathroom, take him out with either the sedative syringe or push him. If he does not see you, he does not count as a witness. Take his clothes and put his body in the container. Walk outside of the bathroom, then go downstairs and through the doorway where a man is working on the door. Find the stairs that lead to the area where the actors' dressing rooms are. When the agent goes in the bathroom, immediately run into the door of the actor you are not supposed to kill. Place the pistol on his table and go outside the door. Turn left and go into the double doors on the right. Go up all the stairs. There is a beam that you are supposed to put a bomb on. Place it there when the worker is not looking, then wait for the actor to shoot the other actor with the real pistol. When the second target realizes he is dead, he will rush down to the body and begin mourning. When he does, detonate the bomb to make the beam fall and kill him. Then, put your suit back from the bathroom and leave.