1998 Chevy Tahoe Brake problem

My wife was driving the truck when it sounded like she ran over a rock. The the right rear brake started making noise and the entire brake system seemed like it was working at 1/2 efficiency. I checked the fluid and it is OK. I also checked the wheels. There is a line that runs to the front of the wheel from inside that seems very loose on the right side. The same line on the left side is not near as loose. When the emergency brake is applied, this line tighens up. What could the problem(s) be?