Oz takes the dream chasers to Castle Nocturnia to meet Grand Inspector Royce. Zoey heads to the Grim Realm to confront the Night Hunter and the rest of the team consults the enigmatic Sandman.
Missing Z-Blob, Mateo tries to free him to the neglect of his dream chaser duties while the team wrestles with an incursion case and a flock of unusual ravens ignites Izzie's suspicions.
The Nightmare King has opened a rift to the waking world and is ready to invade. The dream chasers must make their final stand and defeat the Nightmare King once and for all.
The gang activate Lunia's hourglass and make their way to Castle Nocturnia, hoping to find the key to defeating the Nightmare King. Waiting for them is a mythical creature determined to protect the castle's secrets.
As a night terror rampages through the Fall Festival, the Night Hunter threatens Mateo's family, forcing him to travel to the dream world and confront the Nightmare King alone.
With Lunia's hourglass broken, the gang start their search for the Sandman which leads to a crash landing in the Murky Realm. When the kids' memories begin to fade, they are offered sanctuary by the Never Witch but can she be trusted?