WARNING: The following article contains spoilers for this week's episode of Arrow, the second part of "Elseworlds," which aired Monday on The CW.

Gotham City was finally introduced to the Arrowverse with the second episode of the "Elseworlds" crossover, but Oliver Queen, Barry Allen and Kara Danvers find something there they didn't expect.

While the city has long been depicted as crime-ridden, with colorful villains that prey on the innocent, the Gotham in "Elseworlds" is in even worse shape than that. It's practically a ghost town, where danger lurks around every corner, with only Batwoman remaining as its defender.

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But this week's episode of Arrow not only reveals a desolate Gotham, it teases how the city got that way: Bruce Wayne -- and, by extension, Batman -- has been missing for the past three years, and no one knows where he is. That conveniently explains why the Caped Crusader doesn't get swept up into "Elseworlds," and why he hasn't been lurking on the rooftops of Star City and Central City to keep tabs on Green Arrow and The Flash (in reality, Batman remains off-limits to the Arrowverse). However, that cryptic explanation also raises a larger mystery, as it's not like Bruce Wayne to leave Gotham to ruin, so we can't help but wonder where the Dark Knight has been. Here are a couple of possibilities.

Stuck in Another Reality

DC Comics Return of Bruce Wayne

Batman's world has, in more recent years, been depicted with a veneer of gritty realism, reinforced by Christopher Nolan's hit movie trilogy. However, the Arrowverse has embraced time travel, alternate realities and multiple parallel universes. It's therefore possible that, three years ago, something happened to Batman that left him trapped in another reality. There are certainly multiple comic book stories that have brought the Dark Knight to other worlds, and times.

One of these stories -- The Return of Bruce Wayne by Grant Morrison and such artists as Chris Sprouse, Frazer Irving and Ryan Sook -- even transported Batman back to the beginning of time, and then followed him as he jumped forward through different eras, until he returned to the present day. So what if Batman is actually stuck in the past?

Down for the Count

If Batman has been missing for three years, perhaps it's because he was severely injured by an opponent. In the comic books, Bruce Wayne was away for a long time after the supervillain Bane broke his back. For more than a year, Jean-Paul Valley, took up the mantle of the Bat as Bruce recuperated.

As "Elseworlds" reveals that Batwoman is effectively the sole costumed protector of Gotham City, a similar situation could be the basis for Batman's absence in the Arrowverse. We even saw a quick glimpse of the Bane mask (as featured in Nolan's The Dark Knight Rises) in Arkham Asylum, so we know the villain exists in this universe. But, instead of Jean-Paul, Kate Kane has taken up mantle of the Bat -- allowing Bruce to one day return.

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Similarly, the DC comics series 52 similarly introduced Kate Kane, who suited up as Batwoman while Bruce Wayne was absent from Gotham for a year. He had set off on a quest to train and reconnect with himself alongside Robins Tim Drake and Dick Grayson, leaving Kate to protect the city.

Considering "Elseworlds" features a similar debut for Batwoman, it's possible Bruce has been away all this time to return as an even better crime-fighter. Then again, three years is a long time. When, and if, he does return to Gotham, he may not receive the warmest welcome home from Kate. Because, as we've seen, Gotham is in dire need of help.

The three-night Elseworlds event concludes Tuesday at 8 p.m. ET/PT on The CW with Supergirl.