The Justice League

Once, after the Justice League captured the Joker (Doctor Fate and Supergirl were with them, and of course, the Joker himself), they fell asleep and were then transported somewhere. They lost consciousness, and when they woke up, they realized they were in the wrong place (they ended up in your world. Describe it, how it works, who you are in this world, and everything else so they fully understand the situation).