As Sally Jackson drives Percy and Grover through a violent storm on Long Island, Percy demands answers. Grover admits that he is a satyr and says he has been secretly watching Percy for a long time. Grover also confirms that monsters are real, that humans are often blinded by the Mist, and that the three old women Percy saw were the Fates, a sign that someone is close to death. Sally, frightened but focused, says they must reach the summer camp Percy’s father wanted for him because Percy is no longer safe.

Before Sally can explain more, lightning blasts Gabe’s Camaro off the road into a ditch. Grover is injured, and Percy sees a huge horned figure approaching through the rain. Sally orders Percy to run to the top of the hill, cross the property line marked by a giant pine tree, and head for the farmhouse beyond it. Sally insists that the creature wants Percy, not her, and says she cannot cross the boundary herself, but Percy refuses to abandon either Sally or Grover.

Percy and Sally drag Grover uphill while the monster closes in. Percy recognizes it as the Minotaur, though Sally warns him not to speak its name because names have power. Sally explains that the creature tracks by smell and teaches Percy how to avoid its charge by jumping sideways at the last second. When the Minotaur catches their scent and attacks, Sally tells Percy to split up from them to improve his chances.

Percy dodges one charge, but the Minotaur turns on Sally instead. At the crest of the hill, with the camp farmhouse still too far away, Sally tries to lure the monster away from Grover and orders Percy to run. Percy hesitates, and the Minotaur grabs Sally by the neck. With her last effort, Sally tells Percy to go, then vanishes in a burst of golden light when the monster crushes her. Percy’s grief turns instantly into rage when the Minotaur turns toward helpless Grover.

Percy distracts the Minotaur with his red jacket, leaps onto its back during its charge, and clings to its horns as it crashes into the pine tree. Using sudden strength and instinct, Percy snaps off one horn, then drives the broken horn into the Minotaur’s side as it charges again. The monster disintegrates into dust. Exhausted and devastated, Percy lifts Grover and staggers down to the farmhouse, where he collapses on the porch and briefly sees a familiar bearded man and a blonde girl named Annabeth before losing consciousness.