The patrolling footsteps gradually faded into the distance.
Deathstroke released his grip on the pipes overhead.
Batman, tucked away in a corner, opened his cape as well.
An unconscious prison guard lay in his arms, knocked out by a sedative.
He used hand signals to tell Deathstroke their next route, then tapped his mask three times in a measured rhythm.
"The map indicates that the next patrol won't arrive for at least five minutes. You have plenty of time to move." Alfred's voice came through their earpieces.
The two men moved with light footsteps, their silhouettes slipping in and out of moonlight and shadow.
This was Deathstroke's first visit. Judging by the route they had taken, they had already covered at least a kilometer, circling the asylum's entire ground floor.
If they hadn't needed to maintain absolute silence, he would have asked where Batman intended to take him.
Another patient's shrill howls rang out behind them. He could just make out the sound of a baton striking flesh. He glanced back, catching a flash of electricity in the darkness.
Everything fell silent again.
But just then, Batman stopped abruptly.
Caught off guard, Deathstroke slammed into him and nearly found himself thrown over Batman's shoulder as the man's automatic counterattack kicked in.
He braced a knee against Batman's back and escaped his hold at the cost of a dislocated joint.
"What the hell is wrong with you?"
"You have only yourself to blame for not paying attention!"
Batman lowered his voice and pointed toward the faintly lit corridor ahead.
"That's our destination. Two guards are watching the Hydraulic Door. We'll take one each. Remember, no killing."
He crept toward the wall first, pulled a black rod from his belt, and pressed a button halfway along it. A miniature camera popped out