What is the main storyline of "Batman: Zero Year"?

"Batman: Zero Year" is a 2013-2014 comic book storyline published by DC Comics, serving as a re-imagining of Batman's origin during the New 52 era. It primarily focuses on Bruce Wayne's early days as Batman, specifically his first year of vigilantism in Gotham City, before he became the seasoned hero. The story depicts a city plunged into chaos by the Red Hood Gang and later taken over by the Riddler, with Batman struggling to find his identity and bring hope to a collapsing Gotham.