The Setup: Remember how I told you they had a remote that would disable the blind man's security system? Well, that very same remote also has a panic button that will sound the alarm and call the police. Alex is the last person to have the remote. When he dies at the front door, he drops it right there. Rocky remembers the remote, and the panic button, just as the blind man drags her back into his house. It's the only option she has left.
The Sixth Twist: Just when we think it's over (again), just when the blind man is dragging Rocky back down into the basement, she grabs the remote and hits the panic button. The alarm sounds, and the blind man is rendered helpless with the blaring sounds of the security system.