The key to Batman: Metal #3 is the theme song to Batman 1966

The third installment of Batman: Metal is out this week and like the rest of DC Comics’ dark crossover event, Dark Knights: Metal, it’s pulling references from all over the long history of Batman. But this time, it reaches outside comics entirely to do it.

Series architect and Batman: Metal writer Scott Snyder gave his Twitter followers the scoop more than a week ago:

The scene in question opens the issue, as Wonder Woman, Batman, Superman and Lois Lane gather at the Kent farmhouse for an the debut concert of DCU’s latest up and coming musical group.

Greg Capullo/DC Comics

It’s an adorable gathering of family and friends, and a cute shoutout to a very different era of Batman stories.

But wait a second, at the end of Batman: Metal #2, Batman was sucked into the Dark Multiverse and Wonder Woman and Superman were subdued by the dark god Barbatos. How did we get here?

[Warning: The rest of this post contains spoilers for Batman: Metal #3]

The whole scene is swiftly transmuted into a terrible nightmare Superman is having while in Barbatos’ clutches. Once freed from it, he joins the rest of the beleaguered Justice League, who’ve been trying — and failing — to push back Barbatos’ forces across the world. Their only hope lies in finding remnants of Nth Metal, the only thing that can harm Barbatos and the Nightmare Batmen.

Greg Capullo/DC Comics

But Superman has another goal: He believes that in his nightmare Batman was reaching out to him from the Dark Multiverse itself, calling for help. So Superman, Steel and the Flash break into the Dark Multiverse on a rescue mission.

That rescue mission goes poorly — and that’s where we come back around to the issue’s first scene, and the theme song to 1996’s Batman television show. Batman has been trying to keep the rest of the Justice League away from him from the moment he found out that he’s the key to Barbatos’ dark plans, so as not to put them in more danger.

What Superman thought was a cry for help was just Barbatos’ manipulation. Batman’s actual message wasn’t that he said “Carpe Diem” in Superman’s dream. Batman’s message was the music.

Scott Snyder, Greg Capullo/ DC Comics

What happens after Superman’s mistake pretty dark indeed. Between now and the next installment of the main plot line is the four-issue crossover of “Bats out of Hell,” which pits the Justice League against their Nightmare Batmen counterparts in a battle for the multiverse itself.