In the year
2099,
Miguel O'Hara / Spider-Man 2099 (
Christopher Daniel Barnes) investigates
Alchemax scientist Walker Sloan (
Val Kilmer), discovering that the latter plans to travel back in time to establish Alchemax years before its original founding, rebuild it in his image, and dismantle its corporate rival,
Stark-Fujikawa Industries, before they are established. O'Hara fails to stop Sloan from entering his time gateway and is temporarily trapped between dimensions, where he witnesses visions of his predecessor,
Peter Parker / Spider-Man (
Josh Keaton), being killed by an unknown assailant. Returning to an altered version of 2099, an unaffected O'Hara uses Parker's DNA from Alchemax's archives to establish a mental, chronal link between them across time to warn Parker, now working for Alchemax, of his impending death. However, Parker refuses to heed it and travels to the 66th floor to stop a rampaging
Anti-Venom (
Steve Blum), forcing O'Hara to head to his own 66th floor. Along the way, the Spider-Men discover Sloan has built another gateway in Parker's time, creating a "quantum causality field" and linking their time periods; causing actions in the past to directly alter the future. Arriving at the 66th floor, Parker finds himself confronted by Anti-Venom, Sloan, and Alchemax's head scientist,
Dr. Otto Octavius (
Dave B. Mitchell). He battles Anti-Venom, who drains his powers to the point of death. Before Anti-Venom can kill him, O'Hara pulls Parker through the gateway and places him in a containment unit to heal while he travels to the past and defeats Anti-Venom, breaking the chips that allowed Sloan to control him. Furious at Sloan for using him, Anti-Venom attacks him and Octavius and inadvertently pushes them into the gateway, destabilizing it and trapping the Spider-Men in each other's time periods. While attempting to repair the gateway, O'Hara saves
Mary Jane Watson (
Laura Vandervoort) from a near-death situation while Parker fights clones of
Black Cat (
Katee Sackhoff). All the while, both Spider-Men find themselves being attacked by inter-dimensional tentacles. Using Alchemax's archives, the Spider-Men successfully fix the gateway, though Parker encounters his future self, who used an anti-aging drug to become Alchemax's CEO and wishes to use Sloan's portal for his own ends. Eventually, the Spider-Men successfully return to their original time periods, but a monster resembling Anti-Venom with Octavius' tentacles follows Parker through as the gateway creates a "time storm". Dubbing it "Atrocity" (
Fred Tatasciore), Parker evades the monster while attempting to secure DNA samples from it for O'Hara. Analyzing the samples, O'Hara discovers Atrocity is a combination of Sloan, Anti-Venom, and Octavius and theorizes that forcing it back into the gateway should disrupt the time storm. However, the CEO contacts O'Hara and reveals his intent to harness the storm's quantum energy so he can rewrite history in his image. While Parker lures Atrocity back to the gateway and eventually sends it through, O'Hara does the same with the CEO. This collapses the gateway, ending the time storm and reversing all of Sloan's changes, with only the two Spider-Men remembering the events that were erased. As Parker questions why that is, O'Hara offers to give him a lecture on time travel. ==Development and marketing==