One of Batman: Arkham Knight's pre-order DLC packs allows players to jump into the leather boots of the ever so slightly unhinged Harley Quinn, and information on the game's Amazon store page reveals the playable mission takes place before the events of the main game.
I'm going to stick up a *Spoiler Warning* here, because while the plot info revealed isn't too secretive. It does fill us in on exactly what Harley's up to.
"For the first time in the Arkham series take on the role of Joker’s psychotic side-kick Harley Quinn and wreak havoc inside the Blüdhaven Police Department," reads the synopsis. "With this exclusive Story Pack experience events in the lead-up to Arkham Knight as you infiltrate Blüdhaven to rescue your partner in crime: Poison Ivy. Delve deep into Harley’s demented nature and utilize her devastating baseball bat to smash, crash and bash your way to a friend very much in need."
Blüdhaven is kind of a sister city to Gotham, usually regarded as the domain of Batman's ally Nightwing. Harley and Poison Ivy are best buddies in the comics and animated TV show, so it's nice to see Rocksteady reference their relationship. Yes, I do waste too much of life reading comics, thanks for asking.
The DLC pack contains four challenge packs alongside the story missions. Batman: Arkham Knight recently suffered another delay, but thankfully a much, much shorter one this time - the game's set for release worldwide on June 23.