Batman : The Scarlett Pimpernell
Placing Batman at the time of the French Revolution, Bruce becomes a creature of the night to help innocent people escape the guillotine. Mike W. Barr gives us a pretty solid story I guess. It suffers the same flaws a lot of these "put Batman into an established story" Elseworld books always suffer from.
In this case it is the ScarlettPimpernell. While it seems that Mike Barr had fun with the premise and the set up, when it came to the ending it seems he lost his way. What was left to us, felt forced and unbelievable in the stories context. So what we end up with is an Elseworld that is decent, but does fall short of actually being good.