The Mayhem Collection opens with a single story mission set entirely inside Arkham Asylum, and it plays in two halves. The first half is a quiet, dialogue-driven shift as Dr. Harleen Quinzel, the second is a loud breakout run as Harley Quinn and The Joker. Nothing in it is missable in a way that blocks progress, but the puzzle beats and gadget prompts come fast once the escape starts.
Quick answer: Finish Quinzel’s therapy session, escort Joker to Warden Sharp’s office, then break him out as Harley using the Fun Gun and Boxing Glove, free Poison Ivy, and build the rooftop rocket.
What you need before starting the Arkham Asylum mission
- The full base game of LEGO Batman: Legacy of the Dark Knight.
- The Mayhem Collection DLC, which is included with the Deluxe Edition.
- Standard edition owners can move up with the $24.99 Deluxe Edition upgrade.
- A new save slot and a combat difficulty choice, picked when you launch Mayhem Mode from the main menu.
The DLC is selected from the main menu rather than from a marker in the open world, and the Arkham mission is the first thing it loads. You can grab the collection or the upgrade from the game’s Microsoft Store listing if you are on Xbox.
Harleen Quinzel’s first day and the Joker therapy session
The mission opens on the asylum gates as Dr. Joan Leland welcomes Quinzel, talks through the facility’s more difficult residents, and hands over a security keycard. A guard named Max Security then walks you through maximum security, passing occupied cells that include Killer Croc and Ratcatcher 2.
By the time you find him, Joker is watching the David Endocrine Show. The ensuing therapy uses interactive prompts about comedy, rule-breaking, favorite jokes, dinosaurs, and ice cream. Your choices affect rapport only, not progression, and both characters reveal the same preferences: raptors, cherry swirl ice cream, and the idea of blowing Ace Chemicals up.
Cutscenes here are framed in a 4:3 aspect ratio as a deliberate nod to Batman: The Animated Series, which is where Harley Quinn first appeared.
Escorting Joker to Warden Sharp’s office
Max Security interrupts to report that the warden needs Joker immediately. Control then passes to Quinzel for the first real gameplay section. The route is fixed: cell blocks containing Penguin, Ratcatcher 2, Solomon Grundy and Mutant Leader; the recreation room, where Condiment King, Egghead and Music Meister are killing time; and the outdoor yard, with Henchmaster drilling recruits. Take the stairs on the far side to reach the administration wing.
Inmates along the way have optional interactions. None of them are required to reach the office, so stop for them only if you want the extra banter.
The Amanda Waller cutscene and Harley’s transformation
Inside the office, Amanda Waller announces that Joker is being transferred to Belle Reve for A.R.G.U.S. and Task Force X. Quinzel objects, is dismissed, and is thrown out of the room. She drives into Gotham, takes a jester costume from a novelty shop, and returns to Arkham as Harley Quinn with explosives in hand.
She blows a hole in the wall of Joker’s cell, hands him his purple suit, and the two agree on a going-away party. From this point the mission is a two-character escape with swapping between them.
Joker and Harley gadgets used in the escape
| Character | Gadget or action | Used for |
|---|---|---|
| Joker | Boxing Glove | Pulling down wall panels, hidden levers |
| Joker | Dial lock terminal | Safe-cracking puzzles |
| Harley | Fun Gun (glitter) | Ranged crowd control |
| Harley | Fun Gun (bubblegum) | Jamming gear mechanisms |
| Harley | Pry bar and mallet | Fuse boxes, doors, melee |
Both characters can move while firing, so the escape leans on a run-and-gun rhythm rather than the counter-heavy melee of the main campaign. That same pacing carries over into Mayhem Mode later.
Breaking out of maximum security
Recreation room: graffiti, the DJ booth, and the yard doors
The rec room is where the mayhem meter shows up. Joker can spray a large Joker face across the wall, which pushes the meter up, and the pair can smash the furniture and assemble the loose bricks into a stage and DJ turntable for Music Meister. Building it makes Solomon Grundy break through the gate to dance, and he clears the heavy machinery blocking the exit on his way.
Once the route out is clear, Joker operates the nearby console to unlock the blast doors into the yard.
Yard fight, crew summons, and freeing Poison Ivy
Henchmaster meets you in the exercise yard and introduces the crew summon mechanic. He offers backup recruits, and once assigned you can call player-controlled henchmen into the fight against the waves of Arkham guards crossing the yard. The same system carries into the open world later, where rescued inmates can be trained and added to a customisable crew.
Poison Ivy is held in a sealed containment pod past the yard. The sequence to free her runs in a fixed order.
- Fire Harley’s bubblegum shot into the greenhouse filtration gears to jam them so Ivy can breathe.
- Collect the potted plant from the greenhouse.
- Deliver the plant to Ivy’s containment capsule.
- Ivy powers up, and giant vines tear through the asylum and collapse the structural walls.
Rooftop rocket build and how to confirm the mission is complete
Climb Ivy’s vines up to the rooftop courtyard. Clear the debris scattered across it, then assemble the loose bricks into a motorised Christmas tree rocket. That build is the escape vehicle and the final objective of the mission.
The mission ends on a cutscene: Joker and Harley ride the launching rocket into the night sky mid sing-along while Waller orders an island-wide lockdown, and Colonel Rick Flag moves A.R.G.U.S. agents into position across North Island. You know it registered when control returns at the Amusement Mile entrance instead of inside Arkham.
From there the pair set up a hideout beneath the Funhouse, which becomes the hub you decorate and upgrade. Once that base is established, Mayhem Mode opens up as repeatable, time-limited runs across the locked-down North Island, with studs earned during each run spent back at the hideout on permanent upgrades, customizer props, and 30 new outfits for Joker and Harley.
