Hank Pym travels to East Berlin to rescue an American named Lee Kearns after he was imprisoned by the Reds and accused of spying. After Pym frees Kearns he is told that the Reds accidentally discovered a ray that enhanced the intelligence of animals. The Reds were planning to create an army of gorillas with the advanced intellect. The facility was guarded by the gorilla soldiers and regular soldiers as well. Pym and Kearns manage to turn the ray on the human soldiers who begin to act like apes. Ant-Man the captures the rest of the gorilla soldiers with his climbing wire and notices the Beasts of Berlin are reverting back to regular apes. Pym becomes Giant-Man and destroys the ray device. Kearns and Giant-Man break through the Berlin Wall and return to America.
The Beasts of Berlin were created by Stan Lee and Dick Ayers in 1964 and first appeared in Tales To Astonish #60.