Superman/Batman: Supergirl Comic

Batman has discovered something strange on the bottom of Gotham bay, which leads him to a mysterious and powerful teenaged girl who is bent on destroying Gotham City! Soon, she'll capture the attention of Superman, Wonder Woman and even Darkseid and his Female Furies. What is her connection to Superman? Why does Wonder Woman want to hide her from the outside world? How will Darkseid succeed in recruiting her into doing his bidding? Who is she, and whose side will she end up on?...