The Dreaded Diablo! While on vacation in Transylvania, the Fantastic Four get lost while exploring the forests and come across an ancient castle, however they are told to stay away from it by Baron Hugo. However, that night the Thing answers a call to the castle and unwittingly frees the master alchemist Diablo.
When the FF arrive to see what happened to the Thing they have found that Diablo has almost succeeded in restoring Ben to his human form. When Reed tries to attack Ben for betraying them to Diablo, Ben defends the Alchemist hoping that he can succeed where Reed had failed.
Diablo then begins selling his Alchemy potions the world over and takes Transylvania under his control, meanwhile he tricks Ben into taking a potion that turns him into the Thing once more. The Thing then returns to the FF and the group and leads them in trying to stop Diablo. When Diablo manages to capture his friends, the Thing smashes through the castle and frees his friends, and traps Diablo back in the holding cell he was originally tapped in before bringing the castle down with one powerful punch.
After the Torch melts the castle down to slag, the FF make their leave, finding themselves lost once again in the forest.
