Avengers #333

« Life of the Party »: Releasing the dignitaries unharmed, Dr. Doom reveals that two of the three Dooms are robot doubles, while the real one is wired to a miniature neutron bomb that will detonate if he is attacked. He offers to trade the secret of how he breached the Avengers’ security for the means of interdimensional travel used against the Tetrarchs of Entropy, which he needs to rescue his mother from the Netherworld. Captain America and the Vision expose their opponents as automatons, and Rage, reasoning the third Doom is also fake, smashes it. The real Doom, waiting in a parked limousine, realizes only the absent Thor has the information, deactivates the bomb, and leaves.