When you first start, Ironhide "informs" you that there are three Decepticon drones attacking a structure near you. You have two minutes to get there, but it shouldn't take you that long. After you destroy them a Decepticon SUV comes in. He has a power meter at the top right of the screen. Just strafe back and forth while using your machine gun (or rockets). Then Ironhide will tell you that you are being deployed to Tranquility.