Three girlfriends—Maria, Anna, and Sophia—arrive on the picturesque island of Cayo Guillermo for the long-awaited getaway, but instead of carefree holidays, they encounter a secret that cannot be escaped.
The idyll is shattered by a terrifying discovery: on the beach they find a dead girl with a wound as if inflicted by inhuman power. In the sand, Sophia picks up a strange amulet engraved with the Trixilion—a set of three spirals converging at a single point. Whispers spread across the island: an ancient evil has awakened—Lugaro.
Maria feels an increasingly inexplicable connection to this place. And when Lucia tells her the legend of Mirsele, who once made a bloody bargain with Lugaro, it becomes clear that their arrival on the island is no coincidence.
What do the shadows of old vows conceal? And will Maria manage to figure out what exactly ties her to Cayo Guillermo before Lugaro comes for its next victim?