Think of "Gotham" as the "Batman without Batman" show. Set in Gotham City during the years when Bruce Wayne is still a child, the show centers on young Jim Gordon as he makes his way up through the Gotham City Police Department. Along the way, Jim also encounters many of the characters we know and love (or love to hate) from the Batman universe, from famous rogues to Bruce himself.
The show ran for five seasons on Fox from 2014 to 2019.
