This is Issue #6 of the comic book series "1963", and features several characters from the entire run of the volume.
The "Tomorrow Syndicate" a superhero team somewhat analogous to The Avengers, go on a mission to find their compatriots "Mystery, Incorporated" whom are inexplicably missing. The team heads into a dimensional opening where it is soon discovered there are alternate realities abound, and the Tomorrow Syndicate end up at a type of way station for superheroes and villains who are traversing from one point in time to the next or who are travelling to other dimensions, realities.
A few parodies of other superhero characters, villains, and concepts abound, and the story sort of flounders around a bit, as the team receives little to no assistance in tracking and finding their friends Mystery, Incorporated. The end of the comic does reveal the identity of the mysterious backwards time traveller whom first appeared in Issue #1 of "1963".