The Crown of Nightmares is a gadget, and a crucial part of the plot taking place in MySims Agents. It is said to give unimaginable power to whoever wields it, and pulls the user's nightmares into reality. Morcubus wants this crown to take control of the world. The crown is located somewhere in the world. It is the goal for you, and your organization, to retrieve all these pieces before Morcubus does. You'll visit many places, and each place you visit will have a mystery that you'll have to solve to get another clue to the Crown of Nightmares. An extremely bright red jewel called Fortunite is found encrusted on the center of the crown, which is the source of power that Morcubus is seeking to wield. Once the crown is activated, the crown opens the Nightmare Realm, a dimension that makes all your nightmares come true. The crown was created worked on by a number people, including Paul Wisnewski, who was turned into a Yeti after an accident with the crown, Cyrus Boudreaux, now deceased, and King Mike, a strange man who went insane.
At the end of the game, you successfully take the crown, but Morcubus appears to take it from you. He then prepares to use the crown's power, opening a rift to the Nightmare Realm, but then Evelyn Gray dives at Morcubus, sending them both into the rift. In the process of Evelyn and Morcubus falling into the rift, the crown is knocked out of Morcubus' clutches, closing off the portal, seemingly trapping the pair forever. But later, Walker assigns a dispatch mission where you can choose to save Evelyn, but release Morcubus, or trap Morcubus, but trap Evelyn.