With Rupert Thorne missing and his replacement, Eddie Nygma (The Riddler) now wreaking havoc on Gotham, brutal street violence and brazen robberies escalate and the GCPD is spread too thin to slow it down. To get intel on Thorne's whereabouts and background on his new capo, Nygma, the Batman goes undercover in Blackgate prison in the guise of Matches Malone! 

Disgraced Detective Jim Corrigan volunteers for a prison experiment to redeem himself, but the result is far more horrifying than anyone including the Batman could have imagined.