Fantastic Four #413 "Doom 2099 Vs. The Fantastic Four"
A future version of Doctor Doom from the year 2099 has come to the past in search of a means to save the people of Latveria from a deadly neurotoxin. Already he has attempted to warn his past self of the coming tragedy. Later he discovered that long term exposure to a venom in a specific breed of crab could ultimately make his people immune to the toxin, Doom harvested a massive amount even though exposing it to his people would make them highly addicted to the venom. However in attempting to process the toxin he was interrupted by the Thing and Daredevil, forcing Doom 2099 to inject himself with the toxin in the hopes of finding a means of synthetically reproducing it. Now Doom heads to the one place he know where he can accomplish his task: Four Freedoms Plaza.