Carl's party materializes aboard a dilapidated subway car on the fourth floor, immediately facing monster-infested train cars.

Carl casts Protective Shell while the train moves, turning the stationary bubble into a bulldozer that wipes out pursuing monsters.

The party disembarks at station 83 and reunites with their manager Mordecai inside the floor's safe room.

The party pools their coupon rewards to construct a shared level five communal base with crafting rooms and training facilities.

Carl discovers a posthumous message from his deceased friend Brandon asking him to find Brandon's estranged brother Chris.

The party meets Vernon, a dwarven conductor who explains the train loop system and hints that only a derailment will expose the engineer.

A fire ant trap hidden inside Donut's prize suitcase kills Vernon and forces the party to flee to Banshee Station.

Mordecai attacks the host Chaco the Bard during Carl's Prize Carousel event and is placed in a seven-day suspension.

Carl selects the Dungeon Anarchist's Cookbook from the Prize Carousel and discovers hidden text promising to help destroy the dungeon.

Donut kills the bounty-hunting crawler Ji-Hoon in self-defense at the Desperado Club, earning her first skull icon.

Carl uses custom Jelly Bombs to derail a train, then defeats the mantaur engineer Gore-Gore in a boss battle.

Carl hijacks the Nightmare Express, discovers the Abyss, and realizes the floor is an industrial disposal system rather than a time loop.

Carl broadcasts a mass message to all connected crawlers, detailing four methods to escape the Iron Tangle.

Katia accidentally strikes Hekla with her Rush ability during a confrontation, instantly killing her and jumping from level 24 to 37.

Carl and his party survive the Death Challenge, banish Grull to the Abyss, and use the Nightmare Express to destroy the remaining generators.

Carl and his party arrive on the fourth floor, a massive subway system called the Iron Tangle, and must find stairwells to descend before the level collapses. After establishing a new home base, Carl discovers a heartbreaking message from his late friend Brandon and receives the Dungeon Anarchist's Cookbook, a secret guide promising to help destroy the dungeon from within. A series of escalating confrontations—including a boss battle with the mantaur engineer Gore-Gore and the hijacking of the Nightmare Express—reveals the floor's true industrial mechanics. Carl uses this knowledge to broadcast a mass escape message to all crawlers, while Katia's accidental killing of the treacherous Hekla reshapes the party's power and standing. The climax forces Carl into a Death Challenge against a war god before the party sacrifices the Nightmare Express itself to destroy the floor's generators and finally descend.

The headline events of the Iron Tangle from arrival to escape.

Donut selects the Football Hooligan class and gains the Mascot skill, which buffs the party whenever Mongo attacks.

Carl opens a loot box and receives the Enchanted Necklace of the Haute Bourgeoisie, gaining a dexterity bonus and Talon Strike.

Donut receives the Hole spell from a loot box, and Katia acquires a shapeshifting arm bracer that forms a shield.

A daily dungeon announcement confirms that bounties are now active on the top 10 crawlers on the leaderboard.

The party finds two inactive automatons at Banshee Station and destroys them, harvesting nearly 15 tons of scrap metal.

Mongo reaches his final growth stage, becoming pony-sized and gaining the powerful Earthquake special attack.

The party boards the Dismemberment Limited monorail and battles Flesher undead monsters to protect the operator Levi through a mandatory quest.

Hekla and Brynhild's Daughters arrive at the party's base requesting help to rescue over 1,000 crawlers trapped at station 101.

Carl crafts a massive metal backpack that merges with Katia's body, transforming her into a powerful mass-shifting combat juggernaut.

Carl takes a neural enhancer pill from his Valtay Corporation sponsor box, gaining the ability to see and analyze subspace portals.

Frank Q gives Carl the Ring of Divine Suffering and confesses its curse caused his wife to murder their own daughter.

Carl and Donut record narration for the show Planet Beautiful, and Carl refuses to read an offensive AI-generated script about Earth.

Carl collects over 700 conductor hats and 15 keys from rescued crawlers to distribute to those stranded near the Abyss.

The party repeatedly kills the regenerating gnoll bartender Growler Gary to harvest enough severed hands to operate the rescue carts.

Loita replaces Zev as the party's PR agent, and the party appears on Odette's heavily censored post-floor talk show.

As the party navigates the Iron Tangle, they acquire critical skills, items, and allies that define their entire approach to the floor. From Donut's Football Hooligan class selection to Katia's evolution into a mass-shifting combat juggernaut, these moments of growth form the backbone of the team's survival strategy. Key encounters with NPCs—such as the Dismemberment Limited's tortured operator and the gnoll bartender Growler Gary—reveal both the dungeon's cruelty and its exploitable design. The party's uneasy alliance with Brynhild's Daughters and the dark history embedded in the Ring of Divine Suffering deepen the moral stakes of the crawl. By the close of the floor, the party has shepherded hundreds of crawlers to safety and emerged battered but far more powerful, ready to face a new PR regime as the fifth floor looms.

The encounters, upgrades, and alliances that shaped the Iron Tangle journey.

Katia discovers her constitution has doubled due to a momentum bonus immediately after the party enters the fourth floor.

Carl receives a special apology reward box from the dungeon's AI, containing coupons for free high-value personal space upgrades.

Devastated by Brandon's posthumous message, Carl abandons Mordecai's schedule and spends an hour furiously training his Bare Knuckles skill.

Carl concludes that the dungeon's NPCs are living beings given fabricated memories and backstories to serve the game's narrative.

Elle points out that all transfer stations are located at prime numbers, revealing a hidden mathematical pattern in the Iron Tangle.

Carl uses his 100,000 gold comp chip at the Desperado Club casino and wins a Scroll of Upgrade that massively boosts his Toe Ring.

Katia uses her new makeup table to transform herself into a near-perfect physical replica of the shieldmaiden Hekla.

Imani reveals to Carl that the floor's monsters are controlled through addiction to race-specific opiates distributed at certain stations.

Donut uses her sponsor's sunglasses to spot Hekla secretly firing invisible health-draining bolts at Katia during the rescue train ride.

Carl initiates a dungeon-wide information-sharing network among crawlers by having everyone exchange chat contact details at the Desperado Club.

Donut reaches level 30 and unlocks the Love Vampire skill, which lets her link an enemy to absorb damage for her.

Mordecai returns from his seven-day suspension, and Katia's stored ghoul blood violently erupts throughout the entire room.

Katia folds the floor map to reveal its mirrored geometry, deducing a hidden space between the layers she names the noodle.

Carl accidentally gets pulled through a portal while fighting mantaurs, initiating a Death Challenge against Grull and the Mimic Rex.

On Odette's post-floor show, Odette privately admits she sponsored Hekla and attempts to warn Carl about Brandon's brother before being muted.

Beneath the Iron Tangle's relentless action lies a series of revelations that transform how Carl and his party understand the dungeon and themselves. Carl's grief over Brandon and Katia's existential struggle with identity are mirrored by the dungeon's NPCs, who are revealed to be living beings imprisoned by fabricated memories. Hidden patterns—like prime-numbered transfer stations and the monsters' opiate addiction—expose the floor's deliberately manipulative design beneath its apparent chaos. Katia's breakthrough deduction of the floor's mirrored geometry and the hidden noodle space ultimately unlocks the strategy needed to defeat the final trap. By the epilogue, Carl has committed fully to revolution, and even the post-floor interview is revealed as a stage for corporate censorship and carefully buried secrets.