Warning: SPOILERS for Contagion #1

Iron Fist’s greatest secret could cause the end of the world in Ed Brisson’s Contagion miniseries. The Iron Fists have served the legendary city of K’un Lun for 1,000,000 years, with the first Iron Fist serving alongside the All-Father Odin and the first Ghost Rider as an early Avenger. Over the millennia, the Iron Fists have protected the world from countless threats.

Naturally, the monks of K’un Lun have detailed records of all the forces the various Iron Fists have encountered. 2012’s Avengers Vs. X-Men event, for example, revealed that one past Iron Fist had actually encountered the Phoenix Force. All these records are typically brought to the surface whenever the planet is imperiled again, and frankly Danny Rand - the current Iron Fist - has frequently had cause to wish they’d be a bit more open.

Ed Brisson’s Contagion miniseries launched this week, revealing that K’un Lun has hidden the very existence of a potential world-ending threat. The issue opens with Yu-Ti, the current Thunderer of K’un Lun, summoned to a secret staircase hidden beneath the temple of K’un Lun. It seems that beneath the city are forgotten catacombs, deliberately erased from K’un Lun’s records, and that the monks have unwisely been investigating them for the last few days. They would have been wiser to ask just why the catacombs had been forgotten.

The monks discovered a room at the heart of the catacombs, and once they opened it, they were exposed to a mysterious mycotoxin. A toxic fungus that spreads with skin contact, anyone infected with the mycotoxin appears to lose all control, being driven to spread it. The mycotoxin appears to dislike sunlight, though, and as a result the victims tend to head underground or indoors, and only emerge at night. It doesn’t take long for the mycotoxin to spread to New York City, where it’s contracted by the Mole Man and his Moloids. Soon the Fantastic Four are summoned to investigate - and three of their members fall prey to the mycotoxin.

Contagion appears to be Marvel’s answer to Tom Taylor’s DCeased event, with both stories blending superhero action and classic horror tropes. The key difference, however, is that DC has set their event in a parallel universe; in contrast, Contagion appears to be set in the real Marvel Universe. That will establish limits to the horror, of course; DC has been able to zombify and kill off established heroes, whereas Contagion will have to tread a lot more carefully. But it should also mean that this mysterious mycotoxin, the greatest secret of the Iron Fists, will hopefully have lasting consequences.

Contagion #1 is on sale now from Marvel Comics.

A NEW EVIL BEYOND UNDERSTANDING COMES TO THE MARVEL UNIVERSE! A seemingly unstoppable force has invaded the Marvel Universe, and it’s going to take every hero the streets of New York has to stop it! A strange substance is taking over heroes and citizens alike, draining them of their life force, stealing their knowledge and abilities, and neither science nor magic can stop it! Where did it come from? Can anything destroy it? And who will fall to its awful, overwhelming power?

More: Iron Fist’s Powers & Origin Explained