Angel comes knocking at the Turtle's warehouse door, informing them that something terrible has happened. In the Battle Shell, Angel tells them that her brother Ryan had discovered a gold coin at the Volpehart building and went back to find more, having gone been gone three days. Inside the complex, Angel hears a mysterious voice, beckoning her. She reveals a hidden staircase leading down. They come upon a door, engraved with a message saying to lose all hope for ye for enter. Angel tries to get in but an eye atop a pyramid on the door glowed with a red aura and the skeletons around them come to life. These skeletons prove hard to kill as they are already dead and keep coming back for more. An elderly man descends down the stairs, informing them that they cannot kill the dead and ushers them to follow him. They managed to seal the staircase before the skeletons could get out. Telling them there is no going back from what they've experienced, the man directs them upside. He wasn't at all freaked out at the Turtles, claiming to have seen stranger things in his life. He tells them that the "money" they seek is actually bait. The Turtles and Angel explain themselves and Raph Raph's nightmare that he is The Shredder ask about Ryan. The man says that Ryan was foolish like all the others he tried to warn. He tells them what they are up against... Millennia ago, a glowing red meteor fell to Earth, bringing with it an evil creature, who called forth to humans, with the promise of wealth and power. But the Natives proved too strong of character to its urgings. They crafted a spear-head from the meteor, hoping to slay the beast. Unfortunately, before the deed could be done, the creature called out to men across the sea to Europe, bringing those who desire greed. One such was C.F. Volpehart, who killed the Native warrior carrying the spear and took it. Under the creature's influence, Volpehart gained a vast financial empire, with the creature located beneath the Volpehart building.
The old man says that he is Volpehart's heir, who wanted to kill the monster for avenge his family's legacy. But he was too weak to even use the meteor spear against it, having been too long under its influence.
With little choice, the Turtles resolve to go down into the creature's lair. The old man gives them the meteor spear for their task. As they prepare to go down, Angel asks to come with them but Leo says she must stay topside. As they approach the golden gates, they ward off the skeletons with the spear before entering the creature's lair, finding the meteor bathed in fire like the eye at the top of the pyramid symbol and pods holding the corpses of people from different eras. Suddenly, the creature attacks, with multiple tentacles coming from all directions. They are soon defeated, losing the spear. Leo wakes up in one of the pods, rescued out by Splinter, who had sensed his peril. Suddenly, the creature attacks again; elsewhere, Don encounters Angel, who runs off and jumps into the abyss; Mikey meets Leo. But unfortunately, who was offered by the creatures to join it—which he accepted, having his left arm replaced with three tentacles; Raph encounters Shredder, who he presumes to be behind this. When he knocks his foe's helmet, he finds not Oroku Saki's face, but his own; Leo and Splitner fight the creature but the latter is mortally constricted and Splitner was wounded. Suddenly, Leo finds himself back in his pod, rescued again by Splinter. Leo notes that something seems wrong. At that point, Splinter's eyes turn red and attacks him. He is takes to test in his son and accept to his second test. Leo soon realizes everything is not real and fights back but accidentally stabs Splinter. Reminding himself everything is not real, he wakes up in his pod—for real this time and slices himself out. He then slices his brother's pods and wakes them from their nightmares. Noting that their pods were glowing red, they locate Ryan, who is having a nightmare of Angel being hurt. They convince him that they are part of a very bad dream. Just then, the creature then attacks; Leo finds the meteor spear in the carnage; the creature's whole body then emerges, telepathically trying to seduce Leo into giving in, promising wealth, power and the world. However, Leo fights these temptations and throws the spear into the creature's glowing red eye.
Upstairs, the old man feels that they have succeeded, saying he is free. Angel asks why; the old man reveals that he is in fact C.F. Volpehart and crumbles into dust. The Turtles and Ryan had just come up and Mikey is disgusted after accidentally dancing on Volpehart's remains.
The Turtles are happy to never come back to the building. But as they drive away, a nearby phone rings, answered by a suited man carrying a briefcase. The creature's voice then comes out of it, as the man's eyes turn red.