Old Lady Harley #1

Old Lady Harley and Red Tool visit Batman in an attempt to find out why the supposedly dead Joker has reappeared. When Batman sends them to Catwoman, they visit her in Arkham Asylum only to end up recruiting a small group of Arkham villains to travel back in time to Las Vegas on the day Joker supposedly died. However, they don't arrive in Vegas, but in Blüdhaven instead.