Lexi can't stop killing people. Since turning 16, she's manifested uncontrollable magic that keeps taking lives, stumbled into the nightmarish 13th Hour dimension, and bumped heads with its guardians. With aid from the Department of Metaphysical Security, Lexi and the guardians try to figure out the connection between her volatile magic and the 13th Hour. However, it quickly becomes a race against the clock to stop the 13th Hour from crumbling and unleashing its horrifying "entities" into the world. For Lexi, there's nothing sweet about 16.