Fantastic Four (1961 series) #84

Believing Dr Doom is behind the threat, Reed Richards, the Thing, the Human Torch and his girlfriend Crystal travel to Latveria, the villain's independent state where humanoid robots are awaiting them, cleverly armed with weapons that can neutralize each and everyone of the heroes. After a quick defeat and capture, the team wakes up the next morning in a fine hotel, greeted by the locals who make a parade in their honor. 

Sensing it is a facade for real danger, Reed tries to escape the city, but he's halted by a stun blast. A monitor playing a Dr Doom video clearly states the tyrant's warning: Nobody ever leaves Latveria, or else they die.

Also in this issue: Dum Dum Dugan.

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