Detective Comics Vol. 1 (1937-2011; 2016-) #471

Plot

Bruce Wayne checks into the private hospital Graytowers to recover from injuries he sustained fighting Dr. Phosphorus, but he soon discovers that Hugo Strange is using the facility to turn the rich and influential patients into his mindless slaves. When Strange sics a venomous snake on Batman, which knocks the hero out, Strange uncovers Batman's secret identity.