The next DC animated movie to be released after Batman and Harley Quinn has been officially announced, and it will be an adaptation of the critically-acclaimed Elseworlds graphic novel Gotham by Gaslight.
Until we know more, the only further details will be in the promotional footage included on the Batman and Harley Quinn release.
Gotham by Gaslight itself spawned a sequel called Master of the Future which took on more Jules Verne trappings.
It was published by DC Comics in 1989 as a one-shot, with the story having been written by editor and writer Brian Augustyn.