Spider-Man learns that the Green Goblin is planning to travel across the Multiverse using the Siege Perilous he stole from S.H.I.E.L.D. and the energy of Electro to collect the DNA of other Spider-Men. Spider-Man follows his enemy to the futuristic world of Marvel 2099 (which is drawn in CGI) and helps boost the confidence of Spider-Man 2099. Then he travels to a gender-swapped universe and teams up with Spider-Girl to defeat their world's versions of the Green Goblin.