Satan is sick of being trapped in Hell, and he wishes for freedom. The only key to free him from his prison are the Elements of Harmony, which he must acquire at all costs. So he dispatches his demon horde to get the Elements for him. Three demons (sort of) in particular are accidentally sent forward. Ghost Rider, Hellboy, and Spawn are not amused with their new settings.

Now their only chance at getting back home is making an alliance with the ponies to stem the tide of the growing demon army, and even defeat Satan himself. But unexpected threats are just over the horizon, and an ancient evil has just begun to rise.