Gotham is being overwhelmed by Grimm! They keep appearing in every corner of the city, and the only lead the Dark Knight has is the four mysterious girls he just met. Ruby, Weiss, Blake, and Yang explain to Batman and the assembled Bat-Family how they landed in Gotham. But just as some pieces start to coalesce, a horde of Grimm are converging on the worst possible location: Arkham Asylum!