Peter Parker plans to propose to Mary Jane Watson, who has just made her Broadway musical debut. Meanwhile, a meteorite crashes near the two in Central Park, and an extraterrestrial symbiote attaches itself to Peter's moped. Elsewhere, police pursue escaped prisoner Flint Marko, who climbs a security fence and falls into an experimental particle accelerator that fuses his body with the surrounding sand and allows him to shapeshift at will as the Sandman. Peter's best friend, Harry Osborn, who knows Peter is Spider-Man and holds him responsible for his father Norman Osborn's death, attacks Peter using new weapons based on his father's Green Goblin technology. Harry injures his head on a pipe and suffers from partial amnesia, making him forget his revenge and that Peter is Spider-Man. It later turns out the symbiote enhances Peter's powers as Spider Man, but also bring out the dark side in him.