Warning: contains spoilers for The Joker Presents: A Puzzlebox #4!
In The Joker Presents: A Puzzlebox #4, Harley Quinn's crew has fallen, and the cause is absolutely tragic. Narrated by Joker, the comic shows Harley in pursuit of the puzzle that Riddler may have died over, revealing that her former gang is no more... at least if Joker is to be believed.
The Joker Presents: A Puzzlebox is a crime drama in which the Joker tells stories to the GD's finest, aka Commissioner Gordon and Harvey Bullock. The Riddler is dead and they're trying to find out why, but all of Gotham's villains are suspects. The latest story that Joker tells involves Harley Quinn, with a shocking appearance from a few of her Gang of Harleys. Introduced in Amanda Conner, Jimmy Palmiotti, Chad Hardin, and John Timms' Harley Quinn #16, the Gang of Harleys are a street gang originally assembled to be Quinn's assistants.
Created by Matthew Rosenberg, Jesus Merino, Dani Strips, Ulises Arreola, Jeromy Cox, and Ferran Delgado, The Joker Presents: A Puzzlebox #4 sees Harley come across her fallen gang. While in a cave searching for a mysterious object, she discovers the bodies of Bolly Quinn, Harlem Harley, and Harley Queens. These three are part of the Gang of Harleys, appearing on and off since their creation in 2015. It's a particularly sad "reunion," particularly since Harley could be the one responsible for their deaths.
Bolly is able to speak very briefly before ultimately ing and what she says confuses and upsets the Mistress of Mayhem. She says Harley is responsible for their deaths, which Harley doesn't recall. She re being chased by monsters, but Bolly tells a different story about the gang's boss freaking out inside the cave shortly after entering. This is likely the moment when she put on her miner's hat - which Harley investigates, finding a strange device attached. A mind-control device hidden in headwear is the Mad Hatter's signature move, and sure enough he appears - a perfect target for Harley's newfound anger.
It stands to reason that the Mad Hatter tricked Harley into killing her gang, but this is a story that is being told by the Joker - a highly unreliable source. This is especially true considering he isn't involved in many of the events he is relaying to the police. The previous issue had him describing a meeting involving Black Mask, while this one stars Harley Quinn, Mad Hatter, and Killer Croc. Furthermore, Joker and Harley are broken up in this series, as confirmed by Commissioner Gordon referring to Harley as his "ex-girlfriend." Depending on how these stories connect, there may not actually be a reason for Joker to know anything about Harley's recent adventures.
For all the GD know, Harley isn't even involved in the Riddler's death, but if events did happen as Joker describes, it would be one of the cruelest fates for her crew. The Gang of Harleys have gone through a lot together and even saved Harley after she was kidnapped. Old Lady Harley showed that in that potential future, she left her gang behind because she couldn't face them - though she still considered them her friends. Murdering them, even under mind control, would be one of the darkest betrayals - and biggest tragedies - in Harley's career so far. Harley Quinn may have had a villainous past, but even she has loyalties that she wouldn't want to break. Harley's gang definitely deserved better after everything they've been through together.