Elseworld's Finest: Supergirl & Batgirl (1998-) #1

In an Elseworld where Supergirl was raised by Wonder Woman and Batgirl is a vigilante who keeps Gotham City safe from villainy, there could never be two more different super-heroines. But when the love of Supergirl's life is kidnapped by the Joker, the champions of Gotham and Metropolis must form a reluctant partnership.