Batman: Gotham Knights (2000) #50

An all-new creative team sets off a new direction in this 50^th  issue extravaganza guest-starring 2003's hottest Batman villain: Hush!  He terrorized Batman and his compatriots for months before disappearing without a trace.  Now, Hush resurfaces, prepared to put his next plan for revenge on Batman into motion.  But who is Hush, and what is the real nature of his relationship with the Riddler?