The Nightmare Express is a named steam train on the Iron Tangle, the Fourth Floor of the dungeon. Its route reaches Abyss Station 436, beyond the numbered stops served by ordinary colored lines, and loops through the rail network's switching and repair infrastructure. The train initially carries monsters in freight cars and presents passengers with a dangerous passage from its rear caboose toward the front. After Carl seizes its engine, it becomes a means of investigating the rail system, moving other crawlers, and finally striking at the ghoul infestation threatening the floor. These events take place in The Dungeon Anarchist's Cookbook.
Route and passenger trap
Carl's group first learns of the Nightmare Express through an announcement on the Red Line: transfer station 83 provides access to both the Yellow Line and the named train. At the station, stairs lead to its platform, separate from the ordinary colored-line service. Carl and Donut consider riding it, but its name and their lack of knowledge about named trains give Carl pause. When they inspect its schedule, they find that it arrives only once every hour and a half. The wider tracks, long platform, and absence of an electrified third rail show that it is physically different from the subway trains they have been using.
Katia later studies the available routes and identifies the Express as a possible shortcut to the end of the system. It stops at 436, one number beyond the apparent end of the ordinary line. Reaching it would require transfers that include the Mauve Line, but could take hours instead of days. Carl still cannot assume that the named service is safe. He distinguishes the continuously ascending colored lines from named trains, which run in loops and can return crawlers toward lower-numbered stations. The Express therefore offers a way to change direction within a system that otherwise seems to carry new arrivals away from the stairwells.
By the time the party waits at station 283, Carl has worked out the train's roughly ninety-minute circuit. It passes a station 83, then 283 and 436, before returning through other instances of 283 and 83. The repeated station numbers make the route more complicated than a simple trip up and back along one set of platforms. Its speed is valuable, but its passenger arrangement is designed to make that speed costly. Carl aborts an initial attempt to board when he sees what entering the train would require.
The Express is a black steam locomotive with a cowcatcher and roughly forty cars. Fourteen of its cars appear to contain large monsters; other cars are empty freight wagons. Some loaded cars have open tops, while barriers above them keep people on the platform from simply jumping onto their roofs. Only the rear caboose and a passenger car immediately behind the engine provide visible entrances. The front car's platform door allows exit only. A crawler boarding normally must start at the caboose, climb onto the train, and cross the roofs and narrow gangways above the monster cars to reach the front. Carl sees no reliable way for Donut to bypass that passage with Puddle Jumper, and his Protective Shell cannot last through the entire boarding maneuver.
Carl's seizure of the engine
Carl chooses to intercept the Express before it reaches station 283 rather than make his party traverse the cars. Katia remains on the platform, while Carl takes Donut into the tunnel. Their plan combines Donut's Puddle Jumper with Carl's Protective Shell: the spell moves them farther along the track as the oncoming train passes through the shell, exposing hostile occupants to its barrier. The timing nearly kills Carl. Donut reaches the platform, but Carl is struck by the cowcatcher and carried away on the front of the accelerating locomotive. He survives through his enhanced durability and immediate healing, then has to reach the cab before the uncontrolled engine derails or explodes.
Carl climbs along the outside of the hot boiler and breaks through a cab window. The engineer and a war mage inside have been killed by the encounter with the shell. With neither operator alive, the locomotive is racing ahead under dangerous pressure. Carl's first attempt to slow it makes the pressure gauges climb, and the train's boiler is identified to him as a deteriorating explosive hazard. Pulling the whistle relieves one gauge but leaves the others critical. The controls also include separate braking systems for the engine and the trailing cars, a distinction he does not yet understand.
The person who prevents the train from exploding is Fire Brandy, a lesser demon working inside its boiler as firewoman. She directs Carl to release a valve that the former engineer failed to open, then talks him through stabilizing the pressure and driving at a much lower speed. Her instructions turn the commandeered engine into a usable vehicle. She also tells him how a switch before the next stop can route it to Station Repair, where the train can be serviced. Carl finds a Steam Engineer's Key among the dead operators' possessions, giving him access to employee areas and controls associated with the Tangle's steam trains.
Fire Brandy is part of the engine's operation, not an interchangeable fuel source. Her fire and water magic maintain the boiler, and she warns Carl against overpressurizing it. She is also in labor while he drives. A reserve box of Sheol Bricks can keep the boiler burning if she is unavailable, but she warns that it will not sustain the engine indefinitely without other supplies. Carl takes the box as an emergency measure. His capture has stripped most of the freight cars down to damaged flatbeds, torn the top from the caboose, and left debris along the track. The passenger car behind the engine remains, but its interior is bloodied. The Express has become less of a monster gauntlet for its new operators, though its wrecked cars and vulnerable boiler remain hazards.
The switching station and Abyss Station
The locomotive reaches a switching cavern before Abyss Station. Carl sees targets for Auxiliary Tracks, Station Repair, and Recycle. The auxiliary path seems to connect with still more rail choices; the repair path leads through a large portal; and Recycle points toward a separate route. A switch can be struck from the moving engine by extending a pole from the cab. Other steam trains use the cavern, confirming that the Express is one part of a larger named-train system rather than the only service on its track.
At station 436, Carl leaves the Express parked and climbs a long industrial stairway. It leads to a catwalk around the Abyss, where portals release the passenger cars of ordinary trains into a vast pit. Engine cars are returned to rail yards while the other cars fall among wreckage and janitor ghouls. Carl's ability to examine the portals reveals how passengers with suitable keys or equipment might pass through. He discovers that the souvenir conductor hat issued earlier on the floor can qualify as a key. The Express matters to this discovery because its stop at 436 gives him access to a view of the disposal system from which he can inspect those portals and report possible routes back toward the stairwells.
Carl returns to the engine and drives back to station 283 for Donut and Katia. Katia has cleared much of the wreckage from the track, allowing the damaged train to pass despite occasional jolts. The group then takes it toward Station Repair. Before entering, Carl examines that portal and finds it permits two-way passage under its conveyance and key restrictions, unlike the one-way portals he inspected from the Abyss. The alternative Recycle route leads back toward the pit; choosing the repair route offers a chance to preserve the train and reach the employee network.
The repair portal takes them into a yard crowded with ghouls. There, Widget, a rail worker, initially mistakes the approaching Express for its normal crew's train. He recognizes that the crawlers have taken it, asks after its engineer CrackJack and Fire Brandy, and directs attention to the worsening infestation. The yard's dangers make the train's cab and height useful shelter, but the ghouls can still climb onto it and threaten its occupants. Carl and Donut must coordinate movement through the yard while the rail workers' ability to service or release trains deteriorates around them. Their escape takes the Express onto an employee line beyond the yard.
Transport on the employee line
Once the party has reached the employee network, the Express serves purposes beyond Carl's original trip to stop 436. He learns to reverse its direction using a T-shaped track section and switches, then parks it at station 41 while the party rests and attends to other obligations. The engine can idle with Brandy inside its boiler. This makes it a resource Carl can return to, although its small cab and ruined passenger accommodations limit how many people it can carry safely.
That limit becomes apparent when Carl takes members of Brynhild's Daughters aboard. Carl, Donut, and Katia occupy the cab, while Hekla, Eva, and the others hold onto exterior platforms and rails around the engine. Carl warns them to avoid the hot boiler and tunnel walls and drives slowly. The trip helps move the group along the employee line, but it is precarious transport rather than a restored passenger service. Later, the Express remains parked after ferrying the Daughters toward station 60. Carl and Donut find Fire Brandy still with it; she refuses to let visiting dwarf engineers take it away. Its presence on the employee line becomes important when the crawlers prepare for their final operation.
The train's route and boiler suggest a way to attack the ghoul system. Carl's group plans to send the Express through a portal into the Abyss, where its boiler and additional explosives can detonate amid the monsters and the mechanisms feeding the infestation. Elle is assigned to bring the train toward the operation while others position a portal cart and confront the threat in the trainyard. Fire Brandy initially resists assisting Elle without hearing from Carl, although she allows Elle to move the engine. The train's role depends on the same features that almost killed Carl during its capture: it is a controllable steam locomotive with a boiler capable of a destructive pressure failure, and its rail network reaches the portals at the heart of the Tangle.
Final run
The Express arrives in the trainyard during the confrontation involving the Mimic Rex and the summoned war god Grull. After the immediate fight, Carl confirms that the plan to send the train into the Abyss remains in place. He expects the blast to kill large numbers of monsters there and hopes the added shock will bring down more ghoul generators across the floor. That wider effect is an aim of the plan, not a guarantee known before the train departs.
Carl tries to remove Fire Brandy and her surviving children from the locomotive before its final run. She refuses. After speaking with Tizquick, the dwarf who helped bring the train to the yard, Brandy remembers earlier lives working in other enclosed furnaces and the repeated loss of children she had believed she was raising. She and Tizquick choose to remain aboard despite knowing that the Express will explode. Carl adds his remaining explosive satchels to the train and says goodbye to them. Their decision gives the final journey a different meaning from Carl's original intention to sacrifice an empty machine: the people who keep it moving choose to die with it.
The engine backs to the edge of the yard, sounds its whistle, and races through the portal toward the Abyss. Carl subsequently receives experience notifications for monsters killed there and hears from Bautista that a generator has exploded, allowing his group to move toward the stairwells. Carl does not establish that the province boss has died. The Nightmare Express has carried its crew from a hazardous shortcut through the Tangle to a deliberate strike against the floor's failing infrastructure, with its final passengers determining the cost of that strike for themselves.