Elsa, a shy but smart Chinese girl with short black hair and round glasses, has just moved to Montréal. She loves science and books and carries a glowing sketchbook and pen that reveal her magical powers over ice and light.
One day, while sitting on a bench in Parc La Fontaine, Elsa draws a symbol that suddenly glows and shows a magical map of Montréal.
Yul, her new friend who is part Inuit and Québécois, is an adventurous boy with messy brown hair, wearing a jean jacket and a scarf with traditional patterns. He knows all the secret magical spots in the city.
When he sees Elsa's glowing drawing, he invites her to explore the magical side of Montréal.
Together, they visit an old bookstore near rue Saint-Denis, where a book opens by itself revealing a riddle: "Find the key that sings under the midnight moon."
Yul's ancient compass points to a golden key floating above them surrounded by musical notes. They realize they are inside a magical spell because Elsa's watch shows midnight even though it is only 4 PM.
Later, in a dark alley near the Old Port, shadow creatures called the "Urban Shadows" block their path. Elsa uses her magic pen to freeze the shadows with ice, and Yul creates a shield of light with his compass.
The shadows disappear, leaving behind a broken medallion. Elsa and Yul pick it up, ready to fix it and continue their adventure.
Elsa and Yul climb to the top of Mont-Royal to place the repaired medallion on a stone altar. The city lights up, the shadows vanish, and a giant eagle spirit guardian gives them a feather as a thank you.