In the usually peaceful kingdom of Essendor, people are going missing. The palace makes an urgent decree: all subjects must abide by a strict curfew for their own safety. But for Thandie and her friends, a curfew means more adventure. They dare each other to sneak about the city at night - although Thandie is the only one brave enough to actually do it.

One night, as an eerie fog sets in, Thandie is startled by a strange boy - a boy she's never seen before. He looks about her age, but there's something unsettling about him, leaving Thandie to wonder if he's someone she should trust. Little does she know that this meeting will force her life wildly off-track, pushing her towards an unexpected danger and a fearsome unicorn who is at the very heart of the terrible disappearances she's heard so much about.